Add support for --file,-f configuration_file for reading a list of commands from a file

[zadjii-msft]

From the original spec:

Run these commands in the given Windows Terminal session. Enables opening new
tabs in already running Windows Terminal windows. See Future
Considerations for more details.

[driver1998]

I guess it might be better to be able to read commands from a pipe? So that we can
echo -p "Powershell"; split-pane -p "Ubuntu" | wt.exe

or
type commands.txt | wt.exe

or even
some_launcher | wt.exe
when some_launcher splits the commands?

[zadjii-msft]

From #12583:

There is "persisted window layout" and there are subcommands (sp) to start a new windows with some layout. However, it's not really easy to have a new window with a specific layout.

This feature request asks to load some layout definition file like this (from zellij.dev/documentation/layouts.html):

tabs:
  - direction: Vertical
    parts:
      - direction: Horizontal
        parts:
          - direction: Vertical
          - direction: Vertical
      - direction: Horizontal

for instance via wt -layout preset.yaml. The preset file can be enhanced further with profile name to load, starting directory, or even with a start command (eg, launch some additional task).

This raises the good point - we might want it to be something like a list of actions to perform. We already serialize the window state to JSON, so why can't we just parse a list of actions from a JSON file to execute. This might be more flexible than just a list of subcommands, with the caveat that now all actions need to be able to work before the terminal window is created, not just the few known well-behaving subcommands.