Use that function in the dialog builder instead of having explicit
code in there to check the names.

For now this simply uses a manually curated list of custom widgets. I
used some command line tools to extract the names of custom widgets
used in our .ui files, and then filtered out some I guess (hope) will
not be needed in a mobile app.

For this to work the custom widgets need to have unique names.
Currently that is not the case. Unless I did some mistake, there is
just one case of duplicate name, NotebookbarTabControl, which exists
both in the sfx and vcl libraries. (I simply filtered out that one,
too, for now.)

Change-Id: I29bbf6dfef2b3bde03acfc322495d051a7f275a8