Split compiletests and difftests into parallel CI jobs #442

Job	Run time
Android (ubuntu-24.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	9m 17s
Compiletest (ubuntu-24.04, x86_64-unknown-linux-gnu)	5m 43s
Compiletest (windows-2022, x86_64-pc-windows-msvc)	11m 57s
Test (ubuntu-24.04, x86_64-unknown-linux-gnu)	8m 8s
Compiletest (macOS-latest, x86_64-apple-darwin)	5m 38s
Test (macOS-latest, x86_64-apple-darwin)	6m 35s
Test (windows-2022, x86_64-pc-windows-msvc)	16m 24s
Difftest (ubuntu-24.04, x86_64-unknown-linux-gnu)	8m 49s
Difftest (windows-2022, x86_64-pc-windows-msvc)	15m 16s
Lint	5m 47s
cargo-deny	1m 17s
Difftest (macOS-latest, x86_64-apple-darwin)	6m 14s
test_success	2s
	1h 41m 7s

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