Add token_auth_metadata field for built-in Auth methods

[victorr]

Description

Add token_auth_metadata field for built-in Auth methods.

In tokenutil.go, add support for generic Auth metadata:

• Add a TokenMetadata map[string]string field to struct TokenParams.

• Update method ParseTokenFields to populate the metadata field using request data.

• Update method PopulateTokenAuth to add the metadata to field Auth.Metadata.

• Update other helper methods.

The changes are described in RFC VLT-353.

Please note that external Auth methods and documentation updates will be addressed in separate pull requests.

TODO only if you're a HashiCorp employee

• Backport Labels: If this fix needs to be backported, use the appropriate backport/ label that matches the desired release branch. Note that in the CE repo, the latest release branch will look like backport/x.x.x, but older release branches will be backport/ent/x.x.x+ent.
  • LTS: If this fixes a critical security vulnerability or severity 1 bug, it will also need to be backported to the current LTS versions of Vault. To ensure this, use all available enterprise labels.
• ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature
  of a public function, even if that change is in a CE file, double check that
  applying the patch for this PR to the ENT repo and running tests doesn't
  break any tests. Sometimes ENT only tests rely on public functions in CE
  files.
• Jira: If this change has an associated Jira, it's referenced either
  in the PR description, commit message, or branch name.
• RFC: If this change has an associated RFC, please link it in the description.
• ENT PR: If this change has an associated ENT PR, please link it in the
  description. Also, make sure the changelog is in this PR, not in your ENT PR.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.
• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've documented the impact of any changes to security controls.

Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

[victorr]

In case there are ENT only tests affected by these changes, I have created PR https://github.com/hashicorp/vault-enterprise/pull/8470.

Moreover, I have created a suit of bats tests that cover token auth metadata definition all built-in Auth methods:

test-token-auth-metadata.bats
 ✓ AppRole
   Creating a role
   Reading back the role
   Getting the role id
   Getting a secret ID with its own 'workload' metadata
   Logging in
 ✓ AWS
   Creating a role
   Reading back the role
 ✓ GitHub
   Setting config
   Reading back config
 ✓ LDAP
   Setting config
   Reading back config
 ✓ Okta
   Setting config
   Reading back config
 ✓ RADIUS
   Setting config
   Reading back config
 ✓ SCEP
   Setting config
   Reading back config
 ✓ Cert
   Creating CA certificate role
   Reading back role
 ✓ UserPass
   Creating a user
   Reading back the user
   Logging in
 ✓ Token
   Creating a role
   Creating a token

10 tests, 0 failures

These tests are available in vault-tools (see PR https://github.com/hashicorp/vault-tools/pull/258).

[github-actions]

Build Results:
All builds succeeded! ✅

[github-actions]

CI Results:
All Go tests succeeded! ✅

[stevendpclark]

Looks good to me, some nits but nothing I feel strongly about.

Doc updates will be handled using the new repo I assume?

[victorr]

Yes, the documentation changes will be in the new repository.

[victorr]

TODO: Make this call the helper method.

[victorr]

We have decided to take a slightly different approach, so I am closing this PR without merging.