No error squiggles in c_cpp_properties.json for invalid path or file

[michelleangela]

Type: LanguageService

Repro steps:

1. Set any of properties that takes path or file in c_cpp_properties.json with invalid input

Expected results: error squiggles invalid input

Actual result: no error squiggles

Note: input validation works in configuration UI editor.

[michelleangela]

No bug, the property enableConfigurationSquiggles needs to be set to true to show any squiggles.