improve shell detector with customized terminal.integrated.defaultProfile/profiles

[Qusic]

1. terminal.name can returns '' when terminal activation callback is called and will change to correct value later. however the user can use overrideName to set the value of terminal.creationOptions.name to the shell profile name.
2. terminal.integrated.shell is deprecated but takes precedence over terminal.integrated.defaultProfile.

here are my setup on windows 11. currently detectors will all fail and fallback to powershell.exe in UserEnvironmentShellDetector.

  "terminal.integrated.defaultProfile.windows": "msvc-gitbash",
  "terminal.integrated.profiles.windows": {
    "msvc-gitbash": {
      "overrideName": true,
      "path": "path\\to\\script.bat"
    }
  }

@echo off
call "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliary\Build\vcvars64.bat" > NUL
"C:\Program Files\Git\bin\sh.exe" -i -l

[karrtikr]

Thanks for the PR. However this shell detector is no longer used and is basically dead code: #16023. We plan to remove all other detectors other than the VSCode one, hence closing this.