Figure out solution to two ex icon variants in Claro

Problem/Motivation

There are two different ex.svg icon variants in use in Claro, one with a heavier stroke than the other. In order to avoid naming collisions, the media library uses the heavier icon found in core, and adds color variants there. It might be better to consider renaming these, maybe to something like ex_light and ex_heavy, or approaching it in a different way so they can coexist, and all new Claro-only icons and variants can then be added only to Claro.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet