Support textDocument/foldingRange for imports and multiline top-level definitions #11371

Job	Run time
validate	22s
rustfmt	15s
test (stable, x86_64-pc-windows-msvc)	5m 25s
lint-build	54s
test (stable, x86_64-apple-darwin)	8m 11s
test (stable, x86_64-unknown-linux-musl)	5m 29s
test-wasm	1m 24s
test (stable, aarch64-unknown-linux-gnu)	3m 38s
test (stable, aarch64-unknown-linux-musl)	4m 27s
test (stable, x86_64-unknown-linux-gnu)	4m 21s
test (stable, aarch64-apple-darwin, macos-latest, arm64, cargo, true)	4m 30s
test-projects	2m 38s
	41m 34s

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