Move parse_range() and range_overlaps() into RangeSet.

Also move RangeSet into a header file to make it testable, and add unit
tests.

In RangeSet::Parse() (the former parse_range()), use libbase logging to
do assertions. This has the same effect as the previous
exit(EXIT_FAILURE) to terminate the updater process and abort an update.
The difference lies in the exit status code (i.e. WEXITSTATUS(status) in
install.cpp), which changes from 1 (i.e. EXIT_FAILURE) to 0.

Test: recovery_unit_test
Test: Apply an incremental update with the new updater.
Change-Id: Ie8393c78b0d8ae0fd5f0ca0646d871308d71fff0