Everywhere: Add sv suffix to strings relying on StringView(char const*)

Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).

No functional changes.

Tests/LibCpp/test-cpp-parser.cpp

@@ -31,7 +31,7 @@ TEST_CASE(test_regression)
         auto file_path = directory_iterator.next_full_path();
 
         auto path = LexicalPath { file_path };
-        if (!path.has_extension(".cpp"))
+        if (!path.has_extension(".cpp"sv))
             continue;
 
         outln("Checking {}...", path.basename());