SDK Manager: phase 1 of support for future schemas

This is phase 1 of the support for future schemas:
- introduces a new v2 of the XSD
- handles an unknown XSD and extract its tools elements after
  some hand checks.

TODO in phase 2:
- we still need to iron out the details of the sample node.
- there's no support for samples yet... this commit is not
  about switching the sample code support to the new structure.
- there's no indication to the user that we are handling a new
  schema... there should be some visual clue on why only the
  tools are shown.

SDK BUG 2252825

Change-Id: If1bda26414cfe15275063d3187a98be6301d2992
12 files changed