Merge the Widgets Area Chooser feature plugin. First run, see #25821

git-svn-id: https://develop.svn.wordpress.org/trunk@26054 602fd350-edb4-49c9-b593-d223f7449a82
Produce proper `CAST` for `DECIMAL` and `NUMERIC` in Meta Query. Adds a bunch of unit tests.

Props ericlewis.
Fixes #23033.



git-svn-id: https://develop.svn.wordpress.org/trunk@26055 602fd350-edb4-49c9-b593-d223f7449a82