Use last focused markdown field for quoted reply

What does this MR do and why?

This MR fixes a bug where pressing r after selecting a text for quoted reply within Issues, MRs, and Epics would always add the block quote on main comment form instead of last opened comment form (which can also be discussion reply form).

Screenshots or screen recordings

Screen_Recording_2022-03-21_at_5.08.44_PM

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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.

Related to #292224 (closed)