Add DensityRanker for density descent search #2492

Job	Run time
coverage	1m 34s
pin	2m 57s
tutorials_list	4s
examples	2m 57s
test (ubuntu-latest, 3.12)	1m 20s
test (macos-latest, 3.12)	1m 40s
benchmarks	1m 31s
test (windows-latest, 3.12)	6m 5s
docs	2m 7s
pre-commit	53s
tutorials (tutorials/arm_repertoire.ipynb)	1m 2s
tutorials (tutorials/cma_mae.ipynb)	8m 2s
tutorials (tutorials/features/example.ipynb)	35s
tutorials (tutorials/fooling_mnist.ipynb)	3m 10s
tutorials (tutorials/lsi_mnist.ipynb)	8m 10s
tutorials (tutorials/lunar_lander.ipynb)	9m 27s
tutorials (tutorials/scalable_cma_mae.ipynb)	4m 17s
deploy	0s
	55m 51s

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