Handle macro expansion args in placeholder expansion #225

Job	Run time
Run tests using swift-syntax-dev-utils (Linux)	24m 3s
Validate generated code	2m 57s
Run tests using swift-syntax-dev-utils (Windows)	45m 31s
Test / Linux (5.9 - jammy)	3m 59s
Test / Linux (5.10 - jammy)	3m 55s
Test / Linux (6.0 - jammy)	4m 6s
Test / Linux (6.1 - jammy)	4m 10s
Test / Linux (nightly-main - jammy)	4m 36s
Test / Linux (nightly-6.1 - jammy)	4m 39s
Test / Linux (nightly-6.2 - jammy)	4m 53s
Test / Windows (5.9 - windows-2022)	21m 52s
Test / Windows (6.0 - windows-2022)	19m 51s
Test / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	0s
Test / Windows (6.1 - windows-2022)	19m 58s
Test / Windows (nightly - windows-2019)	17m 25s
Test / Windows (nightly-6.1 - windows-2019)	16m 4s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	4m 53s
Soundness / Format check	41s
Soundness / License headers check	10s
Soundness / Python lint check	6s
Soundness / Shell check	33s
Soundness / Unacceptable language check	6s
Soundness / YAML lint check	5s
	3h 24m 37s

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