Ask to unmute

Is your feature request related to a problem? Please describe.
Sometimes people are muted and we saw them talking on video and would like to unmute them remotely.
In a conversation with many participants, the moderator might want to give voice to people for example after they raised hands.

Describe the solution you'd like
A moderator can click the muted button of participants, either in the video view or sidebar, to trigger "ask to unmute". The participant then receives a dialog box "X asked to unmute, proceed ?". If "Yes" is clicked, their microphone is unmuted, otherwise nothing happens. If the moderator clicks the button again, the dialog disappears (in case of mistake).

Note: For privacy reasons, one should never be able to directly unmute remotely.

Start by tracing the moderator mute controls in the video view and sidebar, then follow how participant state changes are communicated. Define the confirmation dialog and the cancellation behavior described in the issue, while preserving the rule that moderators cannot unmute someone directly. No file or test is named, and the issue has had no recent activity.