Add code-oss icon

Summary: Add the code-oss icons follow the breeze and breeze-dark style

Test Plan:
Latte Dock Preview:

Icons Preview:

Light:

Dark:

Reviewers: VDG, ndavis

Reviewed By: VDG, ndavis

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

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D19324