Recover hidden cycle analytics stages

What does this MR do?

Adds the ability to recover hidden (default only, not custom stages) for cycle analytics

Related to #35823 (closed)

• Adds vuex getters for hidden stages
• Adds recover hidden stage dropdown to the add stage form
• Emits an update stage event when clicking on a hidden stage

Testing

You will need to enable the :customizable_cycle_analytics feature flag

1. Navigate to http://localhost:3001/-/analytics/value_stream_analytics
2. Select a group
3. Hover over any of the stages in the stage list (Issue, Plan, Review, Code etc)
4. Click the more options button (3 vertical dots)
5. Click 'Hide stage'
6. After the data refreshes, the stage should be hidden
7. Click the Add a stage button
8. The 'Recover hidden stage' dropdown should contain the stage that you hid
9. Click the stage
10. After the refresh the stage should appear in the list again

Screenshots

Default	With a hidden stage	With no hidden stages

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