Fix support for multiple LDAP username formats

[donatello]

Description

Fixes support for using multiple base DNs for user search in the LDAP directory
allowing users from different subtrees in the LDAP hierarchy to request
credentials.

- The username in the produced credentials is now the full DN of the LDAP user
to disambiguate users in different base DNs.

Motivation and Context

Existing implementation has an issue that requires the user to be present in each specified base DN.

How to test this PR?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Documentation updated
• Unit tests added/updated

[minio-trusted]

Mint Automation

Test	Result
mint-large-bucket.sh	✔️
mint-fs.sh	✔️
mint-gateway-s3.sh	✔️
mint-erasure.sh	✔️
mint-dist-erasure.sh	✔️
mint-zoned.sh	✔️
mint-gateway-nas.sh	✔️
mint-gateway-azure.sh	❌ more...

11276-55e67f7/mint-gateway-azure.sh.log:

Running with
SERVER_ENDPOINT:      minio-dev4.minio.io:31016
ACCESS_KEY:           minioazure
SECRET_KEY:           ***REDACTED***
ENABLE_HTTPS:         0
SERVER_REGION:        us-east-1
MINT_DATA_DIR:        /mint/data
MINT_MODE:            full
ENABLE_VIRTUAL_STYLE: 0

To get logs, run 'docker cp 451c34775b84:/mint/log /tmp/mint-logs'

(1/15) Running aws-sdk-go tests ... done in 8 seconds
(2/15) Running aws-sdk-java tests ... done in 2 seconds
(3/15) Running aws-sdk-php tests ... done in 2 minutes and 33 seconds
(4/15) Running aws-sdk-ruby tests ... done in 21 seconds
(5/15) Running awscli tests ... done in 2 minutes and 59 seconds
(6/15) Running healthcheck tests ... done in 0 seconds
(7/15) Running mc tests ... done in 3 minutes and 53 seconds
(8/15) Running minio-dotnet tests ... done in 1 minutes and 40 seconds
(9/15) Running minio-go tests ... done in 6 minutes and 25 seconds
(10/15) Running minio-java tests ... FAILED in 8 minutes and 40 seconds
{
  "name": "minio-java",
  "function": "putObject()",
  "args": "[user metadata]",
  "duration": 160,
  "status": "FAIL",
  "error": "error occurred\nErrorResponse(code = AuthenticationFailed, message = -> github.com/Azure/azure-storage-blob-go/azblob.newStorageError, github.com/Azure/azure-storage-blob-go@v0.10.0/azblob/zc_storage_error.go:42\n===== RESPONSE ERROR (ServiceCode=AuthenticationFailed) =====\nDescription=Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.\nRequestId:63ec5170-301e-003f-29a1-eb5a32000000\nTime:2021-01-16T00:47:50.8843629Z, Details: \n   AuthenticationErrorDetail: The MAC signature found in the HTTP request '34dwS1dyoRpNZoI8YFQ13BquDGZkD44nrMrUeXmyk3w=' is not the same as any computed signature. Server used following string to sign: 'PUT\n\n\n128\n\napplication/xml\n\n\n\n\n\n\nx-ms-blob-cache-control:\nx-ms-blob-content-disposition:\nx-ms-blob-content-encoding:\nx-ms-blob-content-language:\nx-ms-blob-content-type:application/octet-stream\nx-ms-client-request-id:cd000242-7749-4b1e-702b-9e54d8cd274a\nx-ms-date:Sat, 16 Jan 2021 00:47:50 GMT\nx-ms-meta-my_header1:a   b   c\nx-ms-meta-my_header2:\"a   b   c\"\nx-ms-meta-my_project:Project One\nx-ms-meta-my_unicode_tag:商å“�\nx-ms-version:2019-02-02\n/minioazure/minio-java-test-3qkmgk9/minio-java-test-162qg5e\ncomp:blocklist\ntimeout:1501'.\n   Code: AuthenticationFailed\n   PUT https://minioazure.blob.core.windows.net/minio-java-test-3qkmgk9/minio-java-test-162qg5e?comp=blocklist&timeout=1501\n   Authorization: REDACTED\n   Content-Length: [128]\n   Content-Type: [application/xml]\n   User-Agent: [APN/1.0 MinIO/1.0 MinIO/2021-01-16T00:14:47Z]\n   X-Ms-Blob-Cache-Control: []\n   X-Ms-Blob-Content-Disposition: []\n   X-Ms-Blob-Content-Encoding: []\n   X-Ms-Blob-Content-Language: []\n   X-Ms-Blob-Content-Type: [application/octet-stream]\n   X-Ms-Client-Request-Id: [cd000242-7749-4b1e-702b-9e54d8cd274a]\n   X-Ms-Date: [Sat, 16 Jan 2021 00:47:50 GMT]\n   X-Ms-Meta-My_header1: [a   b   c]\n   X-Ms-Meta-My_header2: [\"a   b   c\"]\n   X-Ms-Meta-My_project: [Project One]\n   X-Ms-Meta-My_unicode_tag: [商品]\n   X-Ms-Version: [2019-02-02]\n   --------------------------------------------------------------------------------\n   RESPONSE Status: 403 Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.\n   Content-Length: [1092]\n   Content-Type: [application/xml]\n   Date: [Sat, 16 Jan 2021 00:47:50 GMT]\n   Server: [Microsoft-HTTPAPI/2.0]\n   X-Ms-Error-Code: [AuthenticationFailed]\n   X-Ms-Request-Id: [63ec5170-301e-003f-29a1-eb5a32000000]\n\n\n, bucketName = minio-java-test-3qkmgk9, objectName = minio-java-test-162qg5e, resource = /minio-java-test-3qkmgk9/minio-java-test-162qg5e, requestId = 165A8FEE63AC5651, hostId = 8ca07b1e-5dfe-4cbd-aadc-e20ebbd77c36)\nrequest={method=PUT, url=http://minio-dev4.minio.io:31016/minio-java-test-3qkmgk9/minio-java-test-162qg5e, headers=x-amz-meta-My-Unicode-Tag: 商品\nx-amz-meta-My-Project: Project One\nx-amz-meta-My-header1: a   b   c\nx-amz-meta-My-Header2: \"a   b   c\"\nContent-Type: application/octet-stream\nHost: minio-dev4.minio.io:31016\nAccept-Encoding: identity\nUser-Agent: MinIO (Linux; amd64) minio-java/8.0.3\nContent-MD5: A9oFTxee7YVcJ9fWsgQeKg==\nx-amz-content-sha256: 1ff7959f86334ddc5c188a5083268f600146328b2b6c5185e75bf7d9387d6b74\nx-amz-date: 20210116T004750Z\nAuthorization: AWS4-HMAC-SHA256 Credential=*REDACTED*/20210116/us-east-1/s3/aws4_request, SignedHeaders=content-md5;host;x-amz-content-sha256;x-amz-date;x-amz-meta-my-header1;x-amz-meta-my-header2;x-amz-meta-my-project;x-amz-meta-my-unicode-tag, Signature=*REDACTED*\n}\nresponse={code=403, headers=Accept-Ranges: bytes\nContent-Length: 3086\nContent-Security-Policy: block-all-mixed-content\nContent-Type: application/xml\nServer: MinIO\nVary: Origin\nX-Amz-Request-Id: 165A8FEE63AC5651\nX-Xss-Protection: 1; mode=block\nDate: Sat, 16 Jan 2021 00:47:50 GMT\n}\n >>> [io.minio.MinioClient.execute(MinioClient.java:775), io.minio.MinioClient.putObject(MinioClient.java:4547), io.minio.MinioClient.putObject(MinioClient.java:2713), io.minio.MinioClient.putObject(MinioClient.java:2830), FunctionalTest.testPutObject(FunctionalTest.java:763), FunctionalTest.putObject(FunctionalTest.java:890), FunctionalTest.runObjectTests(FunctionalTest.java:3751), FunctionalTest.runTests(FunctionalTest.java:3783), FunctionalTest.main(FunctionalTest.java:3927)]"
}
(10/15) Running minio-js tests ... done in 2 minutes and 42 seconds
(11/15) Running minio-py tests ... done in 17 minutes and 48 seconds
(12/15) Running s3cmd tests ... done in 2 minutes and 18 seconds
(13/15) Running s3select tests ... done in 57 seconds
(14/15) Running security tests ... done in 0 seconds

Executed 14 out of 15 tests successfully.

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Deleting image locally