After git clone flutter/flutter, flutter commands require the use of
powershell to run ps1 scripts. On my corporate workstation, I need to
use a pwsh.bat wrapper to run ps1 scripts.
This PR uses `pwsh` instead of `pwsh.exe` to find and use a bat wrapper
from the path if present.
Closes https://github.com/flutter/flutter/issues/171777.
## Pre-launch Checklist
- [X] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [X] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [X] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [X] I signed the [CLA].
- [X] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.
The check for Git was originally in flutter.bat but was removed by
b84bfa3526
in order to improve performance.
It was later brought back in
bc4fc5ffb9.
However, that change added it to a subroutine in shared.bat. If Git is
not found then shared.bat would exit the shell process to stop retries
of the subroutine.
This PR moves the check back into flutter.bat and exits the script
without quitting the shell.
Fixes https://github.com/flutter/flutter/issues/169784
