feat: Initial implementation of many GCD API's using Swift Concurrency #13

Job	Run time
WebAssembly SDK	1m 17s
tests / Linux (nightly-6.2 - jammy)	1m 9s
tests / Linux (6.1 - jammy)	43s
tests / Linux (nightly-main - jammy)	49s
Soundness / License headers check	5s
Soundness / Format check	33s
Soundness / Broken symlinks check	4s
Soundness / Shell check	31s
Soundness / API breakage check	0s
Soundness / Unacceptable language check	3s
Soundness / Documentation check	36s
tests / Windows (${{ matrix.swift_version }} - windows-2022)	-1s
tests / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	-1s
Soundness / YAML lint check	4s
Soundness / Python lint check	7s
	5m 59s

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