Allow a separate launch mode for when Terminal automatically starts on login

[DHowett]

Ported from MSFT-40653626

It would be nice if we could do these two things:

1. Have a separate launch mode for when Terminal is started on login by our start on login setting.
2. Once we have that, add support for launching minimized. This would let people specify that on startup, Terminal should launch minimized... but it should launch normally otherwise.

[zadjii-msft]

I feel like we've discussed this before on this repo. I bet I linked it to #9992, but I could see this as something separate, tbh.

[zadjii-msft]

notes:

ExtendedActivationKind Enum

name	value	description
StartupTask	1020	The app was activated because the app is specified to launch at system startup or user log-in.

And #14425 adds support for activation event args.

I bet we could:

• Add some enum values to StartOnUserLogin for disabled, normal, minimized, headless
• Around the time of WindowEmperor::HandleCommandlineArgs, we get the Activation args. If it's for a StartupTask, then goody, we can change the logic based on that property:
  • normal: don't change anything
  • headless: don't open a window, manually enable compatibility.allowHeadless in the emperor (at least till the next settings reload)
  • minimized: replace launchMode with minimized for all the windows we're restoring.............
    • Dependent on Add command-line option start terminal minimized #7374
    • Actually, now that I say this, I feel like it doesn't play nicely with state restoration at all. Maybe minimized is a silly value here.

[zadjii-msft]

Copying notes from my whiteboard, because I just need to erase them at this point:

---

Can we tell if we're started for a startupTask just from the AppExecAlias?

if (startupTask
    && settings.StartOnLogin() == Headless
    ) 
{
  don't make window
  start monarch
}

---

Admittedly, that was written a solid year ago, so I'm not entirely sure what it means anymore.