Summary: I changed the `input-mouse` icon so that it would look more like a real mouse. In order to keep the proper icon for the Browse tool, I have to change the icon to `transform-browse`.

Test Plan: {F6874739, size=full}

Reviewers: #okular, #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: ngraham, okular-devel

Tags: #okular

Differential Revision: https://phabricator.kde.org/D21630