feat: datasketches

[SemyonSinchenko]

1. theta(col), theta_intersect(col1, col2), theta_agg(col), theta_estimate(col)
2. hll(col), hll_union(col1, col2), hll_agg(col), hll_estimate(col)

custom aggregations, UDFs

https://docs.rs/datasketches/0.3.0/datasketches/index.html

[SemyonSinchenko]

HLL is here;
For Theta I'm waiting for a new release of the new release of the https://github.com/apache/datasketches-rust

Theta Union was merged to the upstream but did not released yet.