Fix Turbo_Battery artifact time_offset error (+ error handling on 2 other artifact reader)

[mikungg]

Before the fix:

After the fix:

I assume the problem was because the time_offset is undefined

So we need to makes sure we read for the timezone (and set it to UTC if no timezone is found just in case)

Turns out the timezone is America/New_York, this concludes the reader works properly

The image used for the testing:
https://digitalcorpora.s3.amazonaws.com/corpora/scenarios/magnet/2020%20CTF%20-%20Android.tar

[stark4n6]

@mikungg in my opinion, we shouldn't be setting the offset from the timezone from here because it could hold multiple values, we want to set every timestamp to uniform UTC. The timezone_offset was a configurable feature that we are phasing out of but regardless the parser needs to be fixed to account for that.