Print minExtensionVersions to Settings package dump

This is necessary to assert on the value inside a host side CTS test.

Output is formatted like an array of pairs:
    minExtensionVersions=[30=0,31=1]

Bug: 187110971

Test: TODO, will not be merged yet, see bug

Change-Id: Ie609b36100940671915052e9f8fe5ab9a8e56761