* Fix: Prevents crash when table receives mixed data formats
Fixes#20075
* Tests: Adds tests for data format reducers
* Refactor: Updates after PR comments
* Refactor: Missed a couple of places where filtering was needed
- Extracted table panel's merge logic to combine multiple tables into one
- Put the merge logic into the table model as it merges multiple table
models
- make use of merge in Explore's table query response handler
- copied tests over to table model spec, kept essential tests in
transformer spec
