Allow remapping of experimental.repositionCursorWithMouse to use key bindings such as Alt + Left Click

Nobody has claimed this yet.

# Description of the new feature/enhancement

I'm aware that as of now, by setting `experimental.repositionCursorWithMouse` as `true`, we are able to move the cursor to the mouse's position with a simple left click. However, there are times when I want to simply click on the terminal to get it into focus without moving the cursor around. Hence, I think it would be best to let the user choose what keys would be best for them to utilize this feature, for eg. Alt+Left Click/Ctrl+Left Click/Middle Click.

# Proposed technical implementation details (optional)

I'm aware that mouse key bindings are currently not available yet as explained in #1553. However, once they are available, I'd really love it if we can have a command such as `moveCursorWithMouse` and not just `experimental.repositionCursorWithMouse` as a profile setting just like how we have [`showContextMenu`](https://learn.microsoft.com/en-us/windows/terminal/customize-settings/actions#open-context-menu) as a command that can be mapped to a key binding and not just the profile setting `experimental.rightClickContextMenu`.

So maybe we could have something like this in the future:
```json
{ "command": "moveCursorWithMouse", "keys": "alt+left_click" }
```

Review the existing experimental.repositionCursorWithMouse setting and the mouse-binding limitation described in #1553. Compare the proposed moveCursorWithMouse command with the existing showContextMenu command; done means users can choose a mouse/key combination without losing the ability to focus the terminal without repositioning the cursor.

Written by the indexing model from the issue text.