WEB-9801 Dart: hide quick fix if changes should be applied to the external libraries files
(cherry picked from commit 5f358c1b21a263010930c925e77f8c0d5f0e45c0)
WEB-9804 Dart: part path is not resolved correctly if target file is placed inside another directory
(cherry picked from commit 82268a19131a88f1234e94c0365ddd06f52b2488)
cleanup
(cherry picked from commit 1d49b585c8cdbb03ac6dfcea6bad7a1507281d28)