Add the option to create output bundles

[ian-noaa]

Problem

We need to be able to write output bundle tarballs to object storage so that they can be imported by the importer

Solution

We need to:

1. Define what goes into a bundle for METjson2db & VxIngest, as well as any manifest-style files. The end result will be a documented spec for this in VxIngest.
2. Update METjson2db to generate its output in the specified format.

No Go's

Describe any features or behaviors that have been considered and rejected as out of scope for this feature

Additional context

Informed by: NOAA-GSL/VxIngest#548