Audit the system/base libraries

Problem/Motivation

I think we should perhaps have a meta to go through each of the libraries in system/base and decide whether they are still needed, as well as the ones listed here already and in #10, position-container doesn't seem used at all, reset-appearance is used exactly once in Claro, resize only is needed for textareas, etc.

#3432183-18: Move system/base component CSS to respective libraries where they exist →

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet