Generalize categoryFootnotes to work on any sequence #54

Job	Run time
Validate generated code	2m 59s
Run tests using swift-syntax-dev-utils (Linux)	24m 31s
Run tests using swift-syntax-dev-utils (Windows)	46m 50s
Test / Linux (5.8 - jammy)	3m 38s
Test / Linux (5.9 - jammy)	3m 54s
Test / Windows (5.9 - windows-2022)	22m 2s
Test / Linux (5.10 - jammy)	3m 53s
Test / Windows (6.0 - windows-2022)	13m 3s
Test / Linux (6.0 - jammy)	4m 2s
Test / Windows (nightly - windows-2019)	16m 29s
Test / Linux (nightly-main - jammy)	4m 37s
Test / Windows (nightly-6.1 - windows-2019)	14m 36s
Test / Linux (nightly-6.1 - jammy)	4m 57s
Soundness / API breakage check	3m 6s
Soundness / Unacceptable language check	4s
Soundness / Documentation check	4m 46s
Soundness / Broken symlinks check	4s
Soundness / Format check	44s
Soundness / License headers check	9s
Soundness / Python lint check	4s
Soundness / Shell check	31s
Soundness / YAML lint check	3s
	2h 55m 2s

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