Repository navigation

Remove `opaque-debug` and `collectable` (#1452) #377

Job	Run time
test (stable)	1m 36s
test-careful	1m 24s
test (1.85.0)	1m 34s
test-miri (x86_64-unknown-linux-gnu)	51s
test-miri (s390x-unknown-linux-gnu)	1m 10s
minimal-versions / minimal-versions	22s
build (stable, wasm32-unknown-unknown)	12s
build (1.85.0, wasm32-unknown-unknown)	14s
build (1.85.0, thumbv7em-none-eabi)	18s
build (stable, thumbv7em-none-eabi)	14s
	7m 55s