remove OpenTsdbError in favor of TimeseriesError

[agavra]

Summary

After #17 we now have two errors types for timeseries this consolidates the two and renames Error -> TimseriesError so it makes codesearch easier going forward

Related Issues

N/A

Test Plan

Ran existing tests

Checklist

• Tests added/updated
• cargo fmt and cargo clippy pass
• Documentation updated (if applicable)

[hachikuji]

I had wondered if we could just use Error for the public-facing error. That seems conventional in rust. Users can import as TimeSeriesError when there is a conflict.

[agavra]

@hachikuji I don't feel too strongly, I can make that change back. Just seems like we'll have a lot of Error classes in one code base 😅

[hachikuji]

Yeah, that is true. But probably unlikely we would have more than one or two in scope at any time. I feel like rust offers enough alias flexibility like usingtimeseries::Error directly or timeseries::Error as TimeSeriesError that the simpler naming is preferable.