Move audit log app to shared audit events dir

What does this MR do?

This moves the audit logs app into a shared audit events directory that will be used for all audit event views (Admin, Project & Group).

The MR makes the following file structure changes:

• Moves assets folder from javascripts/audit_log/ to javascripts/audit_events/.

• Moves specs folder from frontend/audit_log/ to frontend/audit_events/.

Creates a new shared audit events initializer init_audit_events.js that can be called by different pages.

Renames some of the audit components with the prefix audit_events_.

Issue: #217779 (closed)

Screenshots

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

Closes #217779 (closed)