Browse cleanup (#48136)

* Simplify browse components imports

* Move metrics-related browse components to separate folder

* Move models related browse components to separate subdir

* Split up browse/test-utils

* Move schemas related browse code to separate folder

* Move databases related browse code to separate folder

* Move tables related browse code to separate folder

* Fix import paths

* Avoid drilling into metric module

* Avoid drilling into models module

* Move enterprise tests for browse models

* Format comments

* Remove unused sortModelsByVerification plugin helper

* Support skipToken in useFetchModels

* Simplify models content verification

* Fix filter button query

* Do not filter recent models if there are no verified models

* Use filterButton helper everywhere

* Fixup comment

* Use new var-style color