Add all available options to --help

[Meyhem]

Windows build number: irrelevant
Windows Terminal version (if applicable): 0.11.1121.0

The "-h" CLI option doesn't provide information about all WT's options,
ex: --startingDirectory, -d is missing from there.

It would also be nicer if the "help" would be printed to stdout instead of popping MessageBox which is annoying and does not allow copying.

Steps to reproduce

1. Open any terminal (wt, cmd, PS...)
2. execute "wt -h"

Expected behavior

WT help should display all available CLI options

Actual behavior

WT doesn't display all available CLI options

[DHowett-MSFT]

So, each subcommands has context-specific options. Try wt new-tab -h!

[DHowett-MSFT]

As for the message box, that’s probably the issue that makes us most sad:
#4570 (comment)

Section “displaying an output in a dialog”

[Meyhem]

@DHowett-MSFT Oh, I haven't realized one of the subcommands is ran by default and has the opts. Thanks for explaining.

[DHowett-MSFT]

Sure thing!