Consolidate SQL expr planners so there are one in each module (like a UnicodePlanner rather than a PositionPlanner? #11305
Description
@jayzhan211 do you suggest we have one planner for each module (like a `UnicodePlanner` rather than a `PositionPlanner`?
I think this is similar to what you are proposing with CoreFunctionsPlanner in #11273 (comment) in #11273
We could make this change in a follow on PR too
Originally posted by @alamb in #11243 (comment)