Fix apex package retrieval on boot

There is no API to grab all the installed packages + apexes, so we make
two queries to package manager and merge the results together.

Bug: 163659952
Test: Manually installed new apex version and verified that the correct
apex version was retrieved

Change-Id: I9ca7b50647ff17af73daa9f1b5d08ea480a5f012
1 file changed