Add an OpenGL information tab to Debug Console

Summary:
The new tab shows the information from GLPlatform similar to how it is
shown in the supportInformation. In addition it also lists all available
openGL and EGL/GLX extensions. For that kwinglutils is extended by
functions to return the lists of extensions.

Reviewers: KWin, Plasma, bshah

Subscribers: kwin

Tags: KWin

Differential Revision: https://phabricator.kde.org/D2385