Add Feature Flag Permissions Frontend

What does this MR do?

Adds front-end to ensure users that can not update protected environments can't also update feature flags on those environments.

• If a protected environment is attached to a flag, and a user cannot alter that environment, they cannot:
  • Toggle the flag on the environment
  • Delete the flag
  • Edit the name of the flag
  • Edit the description of the flag

Depends on !10002 (closed)

What are the relevant issue numbers?

#8239

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer