[`pyflakes`] Visit forward annotations in `TypeAliasType` as types (`F401`) #39709

Job	Run time
Determine changes	12s
cargo fmt	18s
pre-commit	3m 16s
cargo build (release)	0s
python package	1m 21s
mkdocs	2m 24s
cargo clippy	2m 2s
cargo test (linux, release)	4m 1s
cargo test (linux)	2m 32s
cargo test (windows)	4m 37s
cargo build (msrv)	5m 21s
cargo fuzz build	5m 27s
cargo test (wasm)	1m 48s
cargo shear	25s
formatter instabilities and black similarity	0s
test scripts	1m 8s
benchmarks	5m 9s
test ruff-lsp	38s
ecosystem	2m 53s
fuzz parser	0s
	43m 32s

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