Compute projected correlation with weights

[camposandro]

Adds a unit test that computes the projected auto-correlation counts with weighted catalogs. Closes #22.

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[github-actions]

Before [818ee31]	After [73f9cd4]	Ratio	Benchmark (Parameter)
2.72±0.6s	2.13±0.5s	~0.78	benchmarks.time_computation
1.66k	2.62k	1.58	benchmarks.mem_list

Click here to view all benchmarks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

see 1 file with indirect coverage changes

[smcguire-cmu]

Code looks fine, but I'm not familiar with the correctness of the tests, so may want to have someone else look over that