Add keyboard shortcuts for opening track context menus

Currently we have two types of track context menus.

1. Main track context menu on the top left corner for seeing all the tracks.
1. Process specific track context menus, when you right click on a track.

Currently, the only way to open these context menus are with clicking with a mouse. There is no way to open them with only keyboard. You can ctrl+click the tracks on macOS to open the process specific ones but still you need a mouse. So it would be great to have keyboard shortcuts for them, so users can do everything with only a keyboard.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-517)