Added new form to saved replies page

What does this MR do and why?

Adds the create a new saved reply form to the saved replies page.

Screenshots or screen recordings

How to set up and validate locally

• Enable the saved_replies feature flag (Feature.enable(:saved_replies))
• 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.