Move all files from the glass repo to a glass subdirectory of the rt-closed repo

In preparation for retiring the glass repo (see RT-18139) we need to move all of the files currently under the glass repo to the rt-closed repo.

The easiest way to do this is to create a glass subdirectory in rt-closed and copy all of the files from glass/** to rt-closed/glass/** keeping the same structure. Then we need to fix the top-level build file and the rt-closed build file and create a build-glass.xml file in rt-closed to call into glass. We can then do any further refinement of the build files as appropriate, but it makes sense to keep functional units like glass in their own sub-directory (much as they are in their own repo today).