Add new allowed_user_key_config field (#1413)

This fix introduces a new configuration block for the
ssh_secret_backend_role resource, which supports the new vault-1.10
updates to the allowed_user_key_lengths parameter. The new config block
is meant to supersede the current allowed_user_key_lengths provider
field.

Example role config:
resource "vault_ssh_secret_backend_role" "demo" {
  name    = "role1"
  backend = vault_mount.demo.path

  allowed_user_key_config {
    type    = "rsa"
    lengths = [2048, 4096]
  }

  allowed_user_key_config {
    type    = "dss"
    lengths = [2048, 4096]
  }
}

* Update docs

* Complete the field name refactoring

* Set the correct field in the legacy case

* Add changelog entry

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 3.5.0 (Unreleased)
+FEATURES:
+* `resource/vault_ssh_secret_backend_role`: support configuring multiple public SSH key lengths in vault-1.10+
+  ([#1413](https://github.com/terraform-providers/terraform-provider-vault/pull/1413))
+
 ## 3.4.1 (March 31, 2022)
 BUGS:
 * `data/azure_access_credentials`: Fix panic when `tenant_id` and `subscription_id` are specified together; add new `environment` override field

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/gosimple/slug v1.11.0
 	github.com/hashicorp/errwrap v1.1.0
 	github.com/hashicorp/go-cleanhttp v0.5.2
+	github.com/hashicorp/go-cty v1.4.1-0.20200414143053-d3edf31b6320
 	github.com/hashicorp/go-hclog v1.0.0
 	github.com/hashicorp/go-multierror v1.1.1
 	github.com/hashicorp/go-retryablehttp v0.7.0
@@ -27,5 +28,6 @@ require (
 	github.com/hashicorp/vault/sdk v0.3.1-0.20211214161113-fcc5f22bea02
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/opencontainers/image-spec v1.0.2 // indirect
+	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3
 	golang.org/x/oauth2 v0.0.0-20211005180243-6b3c2da341f1
 )