chore: remove unused types and constructors, use consistent naming #2430

Job	Run time
test / test-dart-vm (3.0.1)	2m 39s
test / test-dart-vm (stable)	2m 36s
native_test / test-dart-native (macos-latest)	5m 13s
ddc_test / test-dart-ddc (3.0.1, chrome)	4m 19s
native_test / test-dart-native (windows-latest)	4m 31s
ddc_test / test-dart-ddc (3.0.1, firefox)	4m 9s
dart2js_test / test-dart-2js (3.0.1, chrome)	4m 25s
ddc_test / test-dart-ddc (stable, chrome)	3m 54s
dart2js_test / test-dart-2js (3.0.1, firefox)	4m 32s
ddc_test / test-dart-ddc (stable, firefox)	4m 3s
dart2js_test / test-dart-2js (stable, chrome)	4m 24s
dart2js_test / test-dart-2js (stable, firefox)	4m 29s
	49m 14s

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