Merge pull request #1251 from googlefonts/kern-better-categories #3185

Job	Run time
cargo check no std	1m 34s
Build GS and check the result	3m 3s
Rustfmt	1m 6s
cargo check wasm	1m 11s
Clippy lints	1m 32s
cargo test fea-rs	1m 0s
resources/scripts/ots_test.sh	1m 4s
fontbe tests	51s
fontc tests	1m 9s
tests other than fontbe,fontc	2m 7s
	14m 37s

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