Check license header in `flutter analyze` #2291

Job	Run time
test / test-dart-vm (3.9.0)	1m 36s
test / test-dart-vm (stable)	1m 40s
native_test / test-dart-native (windows-latest)	2m 38s
dart2js_test / test-dart-2js (3.9.0, firefox)	6m 34s
dart2js_test / test-dart-2js (stable, firefox)	7m 9s
ddc_test / test-dart-ddc (stable, firefox)	3m 53s
ddc_test / test-dart-ddc (3.9.0, chrome)	3m 55s
ddc_test / test-dart-ddc (stable, chrome)	3m 48s
ddc_test / test-dart-ddc (3.9.0, firefox)	4m 16s
native_test / test-dart-native (macos-14)	3m 9s
dart2js_test / test-dart-2js (3.9.0, chrome)	8m 19s
dart2js_test / test-dart-2js (stable, chrome)	6m 58s
	53m 55s

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