Validate bag SIPs (fixes #947)

[djjuhasz]

This PR uses https://github.com/artefactual-sdps/temporal-activities/blob/main/bagit/validate_activity.go to validate a SIP that is a BagIt bag. I've also added a "classify package" activity to determine if a given package is a BagIt bag.

I've kept the individual commits separate to make it easier to review the changes. I'm inclined to squash the final commit that switches to the Google Distroless Docker image and leave the other commits separate for the merge, so let me know if you think that should change.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 65.14286% with 61 lines in your changes missing coverage. Please review.

Project coverage is 53.51%. Comparing base (1d148a4) to head (59dd99e). Report is 65 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/workflow/processing.go	81.35%	14 Missing and 8 partials :warning:
cmd/enduro-a3m-worker/main.go	0.00%	16 Missing :warning:
cmd/enduro-am-worker/main.go	0.00%	16 Missing :warning:
internal/workflow/local_activities.go	0.00%	7 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #999 +/- ## ========================================== + Coverage 53.31% 53.51% +0.20% ========================================== Files 101 102 +1 Lines 5663 5793 +130 ========================================== + Hits 3019 3100 +81 - Misses 2396 2436 +40 - Partials 248 257 +9 ```

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