Add Setting to disable feed_tokens

What does this MR do?

This MR disables the usage and display of feed_token for RSS/Atom feeds and ICS based calendars.

Closes #231493 (closed)

Screenshots (strongly suggested)

The MR will add an admin setting Disable feed token under Settings/General/Visibilty and access controls/Feed Token:

When feed_tokens are being disabled via this setting Feed token the section under the path /-/profile/personal_access_tokens will disappear and the tokens will stop working.

Screenshot when disabled:

Screenshot when enabled (the default):

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