gitserver: protobuf: relax ArchiveRequest path fields to be bytes instead of string

[ggilmore]

On customer instances and on sourcegraph.com, we get the following errors like the following from the gRPC internal error reporter:

https://cloudlogging.app.goo.gl/mLTBtcFd7w6SgBii9

{
  "insertId": "94nv6f3zi8abqz6s",
  "jsonPayload": {
    "message": "grpc: error while marshaling: string field contains invalid UTF-8",
    "Resource": {
      "service.version": "269484_2024-04-17_5.3-780a5114fefa",
      "service.instance.id": "symbols-0",
      "service.name": "symbols"
    },
    "Function": "github.com/sourcegraph/sourcegraph/internal/grpc/internalerrs.doLog",
    "Attributes": {
      "grpcCode": "Internal",
      "grpcService": "gitserver.v1.GitserverService",
      "nonUTF8StringFields": [
        "paths[5]"
      ],
      "grpcMethod": "Archive"
    },
    "Caller": "internalerrs/logging.go:239",
    "timestampNanos": 1713348262741927000,
    "InstrumentationScope": "gitserver.client.gRPC.internal.error.reporter.streamingMethod.postMessageSend"
  },
  "resource": {
    "type": "k8s_container",
    "labels": {
      "project_id": "src-747bc765eb31a4873e4b",
      "cluster_name": "src-1b4ce535b4573846",
      "container_name": "symbols",
      "location": "us-central1",
      "pod_name": "symbols-0",
      "namespace_name": "src-f7c368f6f7282eff920c"
    }
  },
  "timestamp": "2024-04-17T10:04:22.742097418Z",
  "severity": "ERROR",
  "labels": {
    "k8s-pod/app_kubernetes_io/component": "symbols",
    "k8s-pod/controller-revision-hash": "symbols-66478df6f7",
    "k8s-pod/app_kubernetes_io/instance": "src-bd02273f6b90d1d1beee",
    "k8s-pod/app": "symbols",
    "k8s-pod/deploy": "sourcegraph",
    "k8s-pod/app_kubernetes_io/name": "sourcegraph",
    "compute.googleapis.com/resource_name": "gke-src-1b4ce535b457-nap-n2-highmem-8-7a033d25-4tbj",
    "k8s-pod/statefulset_kubernetes_io/pod-name": "symbols-0"
  },
  "logName": "projects/src-747bc765eb31a4873e4b/logs/stderr",
  "receiveTimestamp": "2024-04-17T10:04:25.081206904Z"
}

This error comes from the gitserver gRPC clients when they tries to send an ArchiveRequest

sourcegraph/internal/gitserver/v1/gitserver.proto

Lines 673 to 684 in 22d9370

	// ArchiveRequest is set of parameters for the Archive RPC.
	message ArchiveRequest {
	// repo is the name of the repo to be archived.
	string repo = 1;
	// treeish is the tree or commit to produce an archive for.
	string treeish = 2;
	// format is the format of the resulting archive (either ZIP or TAR).
	ArchiveFormat format = 3;
	// paths is the list of paths to include in the archive. If empty, all
	// paths are included.
	repeated string paths = 4;
	}

In protobuf, all string fields must be utf-8 encoded. However, the UNIX specification says that filepaths can contain any byte sequence without NULL or /, which includes non-utf8 encoded strings.

So, in order to pass this information along correctly - we need to change the type for paths in ArchiveRequest from string to bytes - which allows for arbitrary byte sequences.

Test plan

Existing unit tests

[sourcegraph-release-bot]

The backport to 5.3.9104 failed at https://github.com/sourcegraph/sourcegraph/actions/runs/8724701853:

The process '/usr/bin/git' failed with exit code 1

To backport this PR manually, you can either:

Via the sg tool

Use the sg backport command to backport your commit to the release branch.

sg backport -r 5.3.9104 -p 61970

Via your terminal

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-5.3.9104 5.3.9104
# Navigate to the new working tree
cd .worktrees/backport-5.3.9104
# Create a new branch
git switch --create backport-61970-to-5.3.9104
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 6a0c465fbd73943cd08e37ced457e232a40c521b
# Push it to GitHub
git push --set-upstream origin backport-61970-to-5.3.9104
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-5.3.9104

If you encouter conflict, first resolve the conflict and stage all files, then run the commands below:

git cherry-pick --continue
# Push it to GitHub
git push --set-upstream origin backport-61970-to-5.3.9104
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-5.3.9104

• Follow above instructions to backport the commit.
• Create a pull request where the base branch is 5.3.9104 and the compare/head branch is backport-61970-to-5.3.9104., click here to create the pull request.

Once the pull request has been created, please ensure the following:

• Make sure to tag @sourcegraph/release in the pull request description.

• kindly remove the release-blocker from this pull request.