Use `arcstr::ArcStr` in block names, UI, and raytracing. #182

Job	Run time
miri	3m 10s
build (ubuntu, stable, locked, true)	1h 18m 33s
no_std	49s
build (windows, stable, locked, false)	26m 11s
build (macos, stable, locked, false)	24m 20s
build (ubuntu, nightly, locked, false)	37m 15s
build (ubuntu, beta, locked, false)	19m 13s
build (ubuntu, stable, latest, false)	23m 31s
build (ubuntu, stable, minimal, false)	29m 30s
deploy	4s
fuzz	19m 1s
	4h 21m 37s

Provide feedback