Add support for sending keystrokes or commands to multiple panes

[Riari]

Edit: Apologies for the duplicate; I did search before but missed the other issues, I think because of differences in phrasing/describing the feature.

Description of the new feature/enhancement

With the current implementation of panes, it's not possible to send keystrokes or commands to multiple panes at once; you have to navigate to each pane to interact with them one by one. It would be nice if we could do one of the following:

A) Send keys to specific panes (a la tmux's send-keys)
B) Focus multiple panes at once in order to interact with them simultaneously
C) Open a text input via a new keyboard shortcut to enter text and hit enter to send it to all panes in the current tab

B or C would be preferable for my use cases (e.g. checking out a specific branch across multiple git repos), but I think any of these would be a welcome addition.

[Don-Vito]

Seems to duplicate #2634

[zadjii-msft]

Yep, this is definitely /dup #2634. Was there a twitter thread about this recently or something? #7919 was also just recently filed about this same thing 🤔

[ghost]

Hi! We've identified this issue as a duplicate of another one that already exists on this Issue Tracker. This specific instance is being closed in favor of tracking the concern over on the referenced thread. Thanks for your report!