[Windows] Add shell symlinks (#2395)

* add shell symlinks

* fix paths

* add a wrapper

* fix target output

* fix tests

images/win/scripts/Installers/Configure-Shell.ps1

@@ -0,0 +1,23 @@
+# Create shells folder
+$shellPath = "C:\shells"
+New-Item -Path $shellPath -ItemType Directory | Out-Null
+
+# add a wrapper for C:\msys64\usr\bin\bash.exe
+@'
+@echo off
+setlocal
+IF NOT DEFINED MSYS2_PATH_TYPE set MSYS2_PATH_TYPE=strict
+IF NOT DEFINED MSYSTEM set MSYSTEM=mingw64
+set CHERE_INVOKING=1
+C:\msys64\usr\bin\bash.exe -leo pipefail %*
+'@ | Out-File -FilePath "$shellPath\msys2bash.cmd"
+
+# gitbash <--> C:\Program Files\Git\bin\bash.exe
+New-Item -ItemType SymbolicLink -Path "$shellPath\gitbash.exe" -Target "$env:ProgramFiles\Git\bin\bash.exe" | Out-Null
+
+# WSL is available on Windows Server 2019
+if (Test-IsWin19)
+{
+    # wslbash <--> C:\Windows\System32\bash.exe
+    New-Item -ItemType SymbolicLink -Path "$shellPath\wslbash.exe" -Target "$env:SystemRoot\System32\bash.exe" | Out-Null
+}