Don't run shell integration on unsupported LanguageMode

Fixes microsoft#158597

Author: Tyriar

src/vs/workbench/contrib/terminal/browser/media/shellIntegration.ps1

@@ -8,6 +8,11 @@ if (Test-Path variable:global:__VSCodeOriginalPrompt) {
 	return;
 }
 
+# Disable shell integration when the language mode is restricted
+if (("RestrictedLanguage", "NoLanguage") -Contains $ExecutionContext.SessionState.LanguageMode) {
+	return;
+}
+
 $Global:__VSCodeOriginalPrompt = $function:Prompt
 
 $Global:__LastHistoryId = -1