Rollup merge of #111151 - ozkanonur:syntax-check-on-bootstrap-scripts, r=Mark-Simulacrum

check bootstrap scripts syntax

Fails bootstrapping if `x`/`x.ps1` scripts are not valid. Currently, it keeps executing lines until the invalid one.

x.ps1

@@ -2,6 +2,11 @@
 
 # See ./x for why these scripts exist.
 
+$ErrorActionPreference = "Stop"
+
+# syntax check
+Get-Command -syntax ${PSCommandPath}
+
 $xpy = Join-Path $PSScriptRoot x.py
 # Start-Process for some reason splits arguments on spaces. (Isn't powershell supposed to be simpler than bash?)
 # Double-quote all the arguments so it doesn't do that.