Add tools icon

Summary:
Adds a `tools` icon for menus that show a list of tools/programs (e.g., the "Tools" menus in Spectacle and KSysGuard)

FEATURE: 390285

Test Plan:
{F6556428, size=full}
{F6556430, size=full}

Reviewers: #vdg, GB_2, ngraham

Reviewed By: #vdg, GB_2, ngraham

Subscribers: ngraham, GB_2, rooty, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D18379