rB8b7cd1ed2a17 broke this for the paint slots
rB4669178fc378 broke this for regular attributes

Name filtering in UI Lists works when:

• [one] the items to be filtered have a name property
  • see how uilist_filter_items_default gets the namebuf
• [two] custom python filter functions (filter_items) implement it themselves
  • if you use filter_items and dont do name filtering there, the default name filtering wont be used

So, two problems with rB8b7cd1ed2a17:

• [1] items to be listed changed from texture_paint_images to texture_paint_slots
  • the former has name_property defined, the later lacks this
• [2] the new ColorAttributesListBase defined a filter_items function, but did not implement name filtering

And the problem with rB4669178fc378:

• it added filter_items functions, but did not implement name filtering.

These are all corrected now.

Fixes T102878