Support "Windows Terminal" as Explorer plugin's "Shell Path"

# Is your feature request related to a problem? Please describe.

I would like to configure the "Explorer" plugin so that "Open with shell" opens via Windows Terminal, using whatever shell is configured as my default.

Unfortunately, two issues arise:

## UI error when trying to configure

Settings -> Plugins -> Explorer -> General -> Shell Path -> click "Select"
Navigate to `C:\Users\cspot\AppData\Local\Microsoft\WindowsApps\`
Choose `wt.exe` (Windows Terminal)
See below error: "The file cannot be accessed by the system"

I suspect this is because the EXEs for Windows Apps are somehow protected so you can't read them but can spawn them.

Even if I manually modify Flow's config file to set the correct path to wt.exe, second issue:

## wt.exe requires `-d` flag to open shell in a directory

`wt -d F:\`: `-d` flag is the way to tell Windows Terminal to open a terminal in a given directory. (in this example, `F:\`)

But I can't configure flags in Flow Launcher.

# Describe the solution you'd like

Modify file picker to avoid the filesystem error.
Add ability to specify CLI flags, not just path to the executable.

# Describe alternatives you've considered

Creating my own shim .exe which delegates to `wt.exe -d`; configuring Flow to launch my shim.

# Additional context

Start in Settings > Plugins > Explorer > General > Shell Path and trace the file picker and shell-launch configuration used by the Explorer plugin. Verify how wt.exe is handled and how the configured path is invoked; done means Windows Terminal can be selected without the filesystem error and launched with the requested directory flag.

Written by the indexing model from the issue text.