Fix #35012 - allow ^\s*$ regex search

Author: roblourens

src/vs/base/common/strings.ts

@@ -221,7 +221,7 @@ export function createRegExp(searchString: string, isRegex: boolean, options: Re
 export function regExpLeadsToEndlessLoop(regexp: RegExp): boolean {
 	// Exit early if it's one of these special cases which are meant to match
 	// against an empty string
-	if (regexp.source === '^' || regexp.source === '^$' || regexp.source === '$') {
+	if (regexp.source === '^' || regexp.source === '^$' || regexp.source === '$' || regexp.source === '^\\s*$') {
 		return false;
 	}