Setup base app for saved replies

What does this MR do and why?

Sets up the base Vue app for viewing, creating, editing, and deleting saved replies in the users preferences.

Screenshots or screen recordings

How to set up and validate locally

• Enable the saved_replies feature flag (Feature.enable(:saved_replies))
• In the Rails console create some saved replies:
  • Users::SavedReply.create!(user_id: 1, name: 'test', content: 'Some content')
• Visit /-/profile/saved_replies

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

#14328 (closed)