Add markdown to proposed enabled extension for remote tests (microsoft#151251)

Author: mjbvz

scripts/test-remote-integration.sh

@@ -63,7 +63,7 @@ else
 	export ELECTRON_ENABLE_LOGGING=1
 
 	# Running from a build, we need to enable the vscode-test-resolver extension
-	EXTRA_INTEGRATION_TEST_ARGUMENTS="--extensions-dir=$EXT_PATH  --enable-proposed-api=vscode.vscode-test-resolver --enable-proposed-api=vscode.vscode-api-tests"
+	EXTRA_INTEGRATION_TEST_ARGUMENTS="--extensions-dir=$EXT_PATH  --enable-proposed-api=vscode.vscode-test-resolver --enable-proposed-api=vscode.vscode-api-tests --enable-proposed-api=vscode.markdown-language-features"
 
 	echo "Storing crash reports into '$VSCODECRASHDIR'."
 	echo "Storing log files into '$VSCODELOGSDIR'."