partition_tools: Add support for partition groups.

lpmake: Add a new -g/--groups parameter to add partition groups. The
syntax is name:size. In addition, a fifth argument can be added to
-p/--partition, to specify a group for that partition. Example:

  lpmake --group google:102400000 \
         --partition system:UUID:readonly:4096:google

In addition, lpdump will now display the groups table and group
assignments.

Bug: 116817738
Test: lpmake with --groups
      lpdump new partition table

Change-Id: Ic1eb995f3bcf5abc7be180ac03c8ba4b82a10045
2 files changed