Audit events for project access tokens

What does this MR do?

Related issue: #230007 (closed)

Add app and audit events for project access token creation and revocation.

App logs can be found in application.log and look like this:

Audit events are available in EE and can be found in Project > Security & Compliance > Audit Events:

Edit: Successful token creation audit event message now includes the access token's scopes:

In the screenshot,

token-scopes has api, read_api, read_repository, and write_repository checked

no-scope has none of the boxes checked

api-token has api checked

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

doc/administration/audit_events.md

@@ -100,6 +100,8 @@ From there, you can see the following actions:
 - Added or removed users and groups from project approval groups ([introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/213603) in GitLab 13.2)
 - Project CI/CD variable added, removed, or protected status changed ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/30857) in GitLab 13.4)
 - User was approved via Admin Area ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/276250) in GitLab 13.6)
+- Project access token was successfully created or revoked ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/230007) in GitLab 13.9)
+- Failed attempt to create or revoke a project access token ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/230007) in GitLab 13.9)
 
 Project events can also be accessed via the [Project Audit Events API](../api/audit_events.md#project-audit-events).