Add nested dropdowns to Filter Condition

[AdRiley]

Pull Request Description

Libs side of nested dropdowns. NOT for the 2025.1 release.

Screen.Recording.2025-03-26.at.09.42.08.mov

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[jdunkerley]

Looks good.

I'd prefer is_nothing and not_nothing in the top level as very useful

Boolean and Floating should not be nested into is/not. I think should appear as Booleand and Numeric.
Likewise empty/not empty should be in Text.