CI/CD Home: Add an alert after a successful commit to master

Summary

Add feedback to the Pipeline Editor so users know when they have committed changes to their default branch.

Description

In the single file editor we have the following behavior after the user commits to master (or their preferred default branch):

desired	current

The alert message: Your changes have been successfully committed. is displayed.

Notes

• This is considered a blocker for our MVC at &4540 (closed)
• There is a parallel discussion at #285499 (closed) about refreshing (or not) the page after committing which may have an impact on this implementation.