Refactor transformer implementations, unifying common components #4480

Job	Run time
Clippy	1m 59s
Check (ubuntu-latest, stable)	1m 40s
Docs	2m 53s
Check (windows-latest, stable)	5m 38s
Check (macOS-latest, stable)	1m 40s
Rustfmt	5s
Test Suite (ubuntu-latest, stable)	5m 30s
Typos	6s
Test Suite (windows-latest, stable)	11m 54s
Test Suite (macOS-latest, stable)	3m 15s
	34m 40s

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