`:PlugStatus`, and I guess basically any command that use `s:with_cd()` internally, won't work when using powershell

Here is a raw display of the error:

The log produced by vim itself shows that the actual command getting execute contains parentheses:
```
Calling shell to execute: "(cd 'd:\\Users\\t0261309\\DEV_COLLECTION\\vim\\vimfiles\\plugged\\vim-code-dark\\' ; & git rev-list --count --left-right HEAD...origin/master) 2>&1 | Out-File -Encoding UTF8 d:\Users\t0261309\AppData\Local\Temp\V7NC049.tmp"
```

Based on the source code implementation of `s:with_cd()` I can see that for powershell, `;` is used to separate two commands. However, the subsequent vim built-in call `system()` will internally add parentheses around the command, and that breaks powershell as a `;` in parentheses is not allowed.

I believe the last E282 error is irrelevant for it is simply because the command is not executed at all and thus no tmp file is created.

A simple fix that I can think of is wrapping the whole cmd with `$(...)`, where `;` can live in, and after the `system()` wrapping, `($(...;...))` works.