Blender Git Loki

Asset Browser: Don't show inapplicable filter and display settings

So far the Asset Browser just showed the same popups and settings as the
File Browser. Not all of them made sense for the Asset Browser though.

* Don't show inapplicable recursion toggle.
* Don't show sorting options, which don't work with assets anyway.
* Don't show the Filter popover, there are currently no applicable items
in there.

Just like in D12057, I decided to add separate classes for the Asset
Browser case.

Differential Revision: https://developer.blender.org/D12059