keep should not block aggregate window optimizations

Currently a query like the following:
```
from
|> range
|> filter
|> keep
|> aggregateWindow
```
will not be optimized as the call to `keep` blocks the `aggregateWindow` from being pushed down. We should have a rewrite rule similar to the group window transpose rule for pushing the `aggregateWindow` past the call to `keep`.

Start by locating the existing group window transpose rewrite rule and the optimizer handling aggregateWindow and keep. Use the query shape in the issue to verify the new rewrite allows aggregateWindow to move past keep and that the aggregate window optimization is applied.

Written by the indexing model from the issue text.