SDK: generate repo using latest schemas when available.

This generates a repository in either v5 or v6 and adjusts
the name/vendor attributes accordingly.

This extracts the support extra in a separate 'repo-extras.xml'
which has an addon.xsd type instead of being a repository.xsd.

Requires sdk.git change Ib0363f06 to build properly.

Change-Id: I250fe7a3ec0dfa490778ae747a1a8f4e536bb395
3 files changed