Operators for bd38d653 (Adds mass and diffusion operators for P2PlusBubble FE space)

MR hyteg!891 (merged) introduced P2PlusBubble elements to HyTeG. This MR adds associated mass and diffusion operators (2D, w/o blending, w/ AnnulusMap). This MR supersedes !28 (closed). The latter had produced operators that were not usable, because they contained an out-dated include path for P2PlusBubbleFunction.hpp. This was fixed in hog@dd443167, the version used for this MR.

Operators generated for bd38d653 by pipeline #77998.