Handle macro expansion args in placeholder expansion #226

Job	Run time
Run tests using swift-syntax-dev-utils (Linux)	24m 5s
Validate generated code	2m 55s
Test / Linux (5.9 - jammy)	3m 53s
Run tests using swift-syntax-dev-utils (Windows)	47m 28s
Test / Linux (5.10 - jammy)	3m 55s
Test / Linux (6.0 - jammy)	4m 20s
Test / Linux (6.1 - jammy)	4m 7s
Test / Windows (5.9 - windows-2022)	23m 1s
Test / Linux (nightly-main - jammy)	4m 55s
Test / Windows (6.0 - windows-2022)	17m 37s
Test / Windows (6.1 - windows-2022)	16m 2s
Test / Linux (nightly-6.1 - jammy)	4m 57s
Test / Windows (nightly - windows-2019)	15m 4s
Test / Linux (nightly-6.2 - jammy)	4m 52s
Test / Windows (nightly-6.1 - windows-2019)	14m 34s
Test / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	0s
Soundness / Documentation check	5m 11s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	4s
Soundness / License headers check	10s
Soundness / Unacceptable language check	4s
Soundness / Format check	42s
Soundness / Python lint check	5s
Soundness / Shell check	32s
Soundness / YAML lint check	3s
	3h 18m 36s

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