[red-knot] Rework `Type::to_instance()` to return `Option<Type>` #41847

Job	Run time
cargo fmt	23s
Determine changes	9s
mkdocs	2m 36s
cargo build (release)	0s
pre-commit	3m 23s
python package	1m 21s
cargo clippy	1m 50s
benchmarks	4m 27s
cargo build (msrv)	2m 59s
cargo fuzz build	4m 22s
cargo shear	2m 19s
cargo test (linux)	2m 7s
cargo test (linux, release)	4m 8s
cargo test (wasm)	1m 44s
cargo test (windows)	4m 28s
test scripts	1m 1s
formatter instabilities and black similarity	0s
test ruff-lsp	46s
ecosystem	22s
fuzz parser	0s
	38m 25s

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