refactor: install clang tools on demand #594

Job	Run time
powerpc-unknown-linux-gnu	3m 18s
x86_64-unknown-linux-gnu	1m 55s
aarch64-apple-darwin	2m 27s
x86_64-unknown-linux-musl	3m 30s
powerpc64le-unknown-linux-gnu	3m 32s
arm-unknown-linux-gnueabihf	3m 30s
armv7-unknown-linux-gnueabihf	3m 29s
aarch64-unknown-linux-gnu	3m 28s
arm-unknown-linux-gnueabi	3m 25s
aarch64-unknown-linux-musl	3m 36s
x86_64-apple-darwin	3m 8s
x86_64-pc-windows-msvc	2m 36s
aarch64-pc-windows-msvc	3m 6s
s390x-unknown-linux-gnu	3m 28s
publish	0s
	44m 28s

Provide feedback