Add support for SE-0460 @specialized #204

Job	Run time
Run tests using swift-syntax-dev-utils (Linux)	23m 7s
Run tests using swift-syntax-dev-utils (Windows)	48m 4s
Validate generated code	2m 47s
Test / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	0s
Test / Linux (5.9 - jammy)	3m 58s
Test / Windows (5.9 - windows-2022)	24m 46s
Test / Linux (5.10 - jammy)	3m 46s
Test / Windows (6.0 - windows-2022)	20m 42s
Test / Linux (6.0 - jammy)	4m 11s
Test / Windows (6.1 - windows-2022)	20m 15s
Test / Linux (6.1 - jammy)	3m 54s
Test / Windows (nightly - windows-2019)	16m 3s
Test / Linux (nightly-main - jammy)	4m 43s
Test / Windows (nightly-6.1 - windows-2019)	14m 47s
Test / Linux (nightly-6.1 - jammy)	4m 51s
Soundness / Documentation check	5m 27s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	3s
Soundness / License headers check	12s
Soundness / Unacceptable language check	5s
Soundness / Format check	39s
Soundness / Python lint check	5s
Soundness / Shell check	36s
Soundness / YAML lint check	4s
	3h 23m 5s

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