[icons/media.svg] Add 16 & 32px icons, update style

Summary: Fixes blurry icons in the desktop shell

Test Plan:

Examples of fuzzy icons:

task manager

media player widget

Fixed:

Reviewers: VDG, Plasma, ngraham

Reviewed By: VDG, ngraham

Subscribers: ngraham, kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D24627