Add a helper to sanity check extension installs

src/modules/cmdpal/check-extensions.ps1

@@ -0,0 +1,33 @@
+# Use me to check if extensions deployed correctly
+
+$gitRoot = git rev-parse --show-toplevel
+Write-output "Checking repo root at $gitroot"
+$extensionsRoot = "$gitroot\x64\Debug\WinUI3Apps\CmdPalExtensions"
+Get-ChildItem -Path $extensionsRoot | ForEach-Object {
+    $extensionName = $_.Name
+    $extensionName
+    $extensionAppx = $_.PsPath + "\Appx"
+    if ((Test-Path $extensionAppx) -eq $false) {
+        Write-Host "  `e[31;1mUNEXPECTED`e[0m: There was no Appx/ directory. Make sure you deploy the package!"
+    }
+    else 
+    {
+        # Write-Host "`e[90m  Found Appx/ directory`e[0m"
+        $appxWinmd = $extensionAppx + "\Microsoft.CmdPal.Extensions.winmd"
+        if ((Test-Path $appxWinmd) -eq $false) {
+            Write-Host "  `e[31;1mUNEXPECTED`e[0m: Did not find Microsoft.CmdPal.Extensions.winmd"
+        }
+        else {
+            # Write-Host "`e[90m  Found the winmd`e[0m"
+            Write-Host "`e[92m  Everything looks good`e[0m"
+        }
+    }
+}
+$winmdRoot = "$gitroot\\x64\Debug\Microsoft.CmdPal.Extensions"
+$winmdOutput = "$winmdRoot\Microsoft.CmdPal.Extensions.winmd"
+if ((Test-Path $appxWinmd)) {
+    Write-Host "Found Microsoft.CmdPal.Extensions.winmd where it's supposed to be"
+}
+else {
+    Write-Host "  `e[31;1mUNEXPECTED`e[0m: Did not find Microsoft.CmdPal.Extensions.winmd where it's supposed to be built! Did you build Microsoft.CmdPal.Extensions?"    
+}