Add grammar docstrings to QASM3 parser #9607

Job	Run time
Format	14s
Build and test (windows-latest)	2m 2s
Format Q# Files	51s
Build and test (ubuntu-latest)	2m 16s
Clippy	1m 14s
Build and test (macos-14)	1s
Integration tests (windows-latest)	1m 47s
Rust Unit tests (windows-latest)	1m 57s
Integration tests (ubuntu-latest)	2m 15s
Check web files	30s
Rust Unit tests (ubuntu-latest)	2m 13s
Integration tests (macos-14)	1s
Rust Unit tests (macos-14)	1s
Status Check	1s
	15m 23s

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