Add asv benchmarks

[manodeep]

Is your feature request related to a problem? Please describe.
It is hard to keep track of performance improvements/regression in Corrfunc.

Describe the solution you'd like
An automated CI job that (relative) benchmarks both new commits and has a history of benchmark jobs to monitor Corrfunc performance. This would have to run on CI, and, therefore would need relative benchmarking, i.e., compare performance between two commits. Should be achievable with asv

Describe alternatives you've considered
N/A

Additional context
We can follow the PR to scikit-image here - scikit-image

Blog post here (google cache): https://webcache.googleusercontent.com/search?q=cache:Rlb4bLUZGgEJ:https://labs.quansight.org/blog/2021/08/github-actions-benchmarks&cd=2&hl=en&ct=clnk&gl=au&client=firefox-b-d

[manodeep]

asv run vx.y..master can be used to run benchmarks for all commits starting from a specific one. The --steps can be used to specify the number of (uniform) increments to use, since the benchmarks otherwise might time out