Add a dumpsys for UsageStatsDatabase info.

'dumpsys usagestats file [user] [interval] [filename]' added.
When all options are specified, this command dumps all usage stats
information stored in the specified filename.
If the filename is not specified, information of all files for the
specified interval is dumped.
If the interval is not specified, information of all files in all of the
intervals for the specified user is dumped.
If the user is not specified, information for all users is dumped.

Also added 'dumpsys usagestats database-info [user]'. This simply
connects the existing dump in UsageStatsDatabase.
If the user is not specified, information for all users is dumped.

Bug: 131923219
Test: various combinations of the dumpsys command added
Change-Id: Id2c2b20e07f9ab0e1a577e45fba199d565532b7b