CMake

ksparse recovery sketch with some more updates #1120

Job	Run time
full-build (ubuntu-latest, "-DL0_SAMPLING")	16s
full-build (ubuntu-latest, "-DNO_EAGER_DSU")	14s
full-build (ubuntu-latest, "")	16s
full-build (ubuntu-20.04, "-DL0_SAMPLING")	30s
full-build (ubuntu-20.04, "-DNO_EAGER_DSU")	30s
full-build (ubuntu-20.04, "")	31s
	2m 17s

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