Support various LSP operations on clause guards #11437

Job	Run time
lint-build	57s
test-wasm	1m 22s
validate	34s
rustfmt	10s
test (stable, x86_64-apple-darwin)	9m 53s
test (stable, aarch64-unknown-linux-gnu)	3m 48s
test (stable, x86_64-unknown-linux-gnu)	4m 19s
test (stable, x86_64-pc-windows-msvc)	8m 59s
test (stable, x86_64-unknown-linux-musl)	6m 24s
test (stable, aarch64-unknown-linux-musl)	4m 28s
test (stable, aarch64-apple-darwin, macos-latest, arm64, cargo, true)	8m 6s
test-projects	2m 52s
	51m 52s

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