**Summary** Add support for the following aggregations in the new python implementation currently already available in the rust implementation [documented](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#aggregation-functions). **Changes** - [x] [count](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#count) - [x] [count_if](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#count_if) - [x] [max](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#max) - [x] [mean](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#mean) - [x] [min](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#min) - [x] [stddev](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#stddev) - [x] [variance](https://kaskada.io/docs-site/kaskada/main/fenl/catalog.html#variance)
