Introduce FixIt.Change.replaceText #127

Job	Run time
Validate generated code	2m 58s
Run tests using swift-syntax-dev-utils (Linux)	24m 46s
Run tests using swift-syntax-dev-utils (Windows)	40m 35s
Test / Linux (5.9 - jammy)	3m 50s
Test / Linux (5.10 - jammy)	3m 49s
Test / Windows (5.9 - windows-2022)	22m 10s
Test / Linux (6.0 - jammy)	4m 11s
Test / Windows (6.0 - windows-2022)	24m 25s
Test / Linux (nightly-main - jammy)	4m 40s
Test / Windows (nightly - windows-2019)	15m 52s
Test / Linux (nightly-6.1 - jammy)	4m 46s
Test / Windows (nightly-6.1 - windows-2019)	15m 17s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	5m 12s
Soundness / Format check	42s
Soundness / License headers check	10s
Soundness / Shell check	30s
Soundness / Unacceptable language check	5s
Soundness / YAML lint check	2s
Soundness / Python lint check	5s
	2h 54m 9s

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