## What

Allow aggregate scan planning warnings to be disabled.

## Why

The aggregate scan planning warnings are helpful for users who:
1. are designing queries to get ideal performance
2. are using `pdb.agg` (in which case the aggregate scan _must_ be used)

...but they are not necessarily helpful for users who have turned on the
scan globally in order to get wins whenever possible, without
necessarily focusing on the performance of individual queries.

## How

Added the `paradedb.check_aggregate_scan`, which is obeyed unless
`pdb.agg` is used (in which case the scan is the only possible way to
satisfy a query).

(cherry picked from commit c8b01e2)