readyset-dataflow: window function initial support

Handle lowering from mir to dataflow and execution
of window function:

- Initial support for window functions (empty OVER, `PARTITION`s,
  and `ORDER BY`)
- Handle NULLS in Window Functions
- In non-cumulative windows (no `ORDER BY`), since any change
  is likely to change the values of the entire partition, we send
  -ve diffs of the partition (not the entire window), process
  the changes, then send +ve diffs of the partition.
- In cumulative windows, we merge the sorted partition
  and the changes, then send partition diffs after the earliest
  change. This means that, for example, appending a row to the end
  of a partition will only send one +ve diff and no -ve diffs.
- More logictests

Fixes: REA-5790, REA-5791, REA-5794

Release-Note-Core: Readyset now supports Window Functions
  following pattern `function OVER([PARTITION BY {expr, ..}]
  [ORDER BY {expr, ..}])` where `function` is one of `COUNT`, `SUM`,
  `AVG`, `RANK`, `DENSE_RANK`, `ROW_NUMBER`, `MIN`, or `MAX`.

Change-Id: I82aaa403dddaf5f3df23f0d0dc2cb4f753d9ce1b
Reviewed-on: https://gerrit.readyset.name/c/readyset/+/9691
Tested-by: Buildkite CI
Reviewed-by: Michael Zink <michael.z@readyset.io>

Author: MohamedAbdeen-rs