AK: Add case insensitive version of starts_with

Author: https://github.com/Lubrsi
Commit: a5ecb9bd6b
Pull-request: https://github.com/SerenityOS/serenity/pull/2842

AK/FlyString.cpp

@@ -99,6 +99,11 @@ bool FlyString::equals_ignoring_case(const StringView& other) const
     return StringUtils::equals_ignoring_case(view(), other);
 }
 
+bool FlyString::starts_with(const StringView& str, CaseSensitivity case_sensitivity) const
+{
+    return StringUtils::starts_with(view(), str, case_sensitivity);
+}
+
 bool FlyString::ends_with(const StringView& str, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::ends_with(view(), str, case_sensitivity);