Feat pb 1160 harvest package data

[msom]

This PR adds a stac_harvest management command to the distributions application to sync package distributions with service-stac.

The command uses the STAC collection ID as the package distribution slug and relies on the managed_by_stac flag to identify package distributions managed by service-stac.

The command ensures that for each STAC collection, a corresponding package distribution exists by:

• Creating new package distributions if no package distribution matches the STAC collection.
• Updating package distributions with a matching STAC collection. This will update the dataset and force the managed_by_stac flag to be set.
• Removing package distributions with the managed_by_stac flag set but no matching STAC collection.

Assumptions and Behavior

• Dataset Matching: A package distribution is created only if a dataset exists with a slug matching the STAC collection ID. If no such dataset exists, no package distribution will be created.
• Provider Matching:
  • Each STAC collection must have exactly one provider, which should match the dataset’s provider (by its English name).
  • If a mismatch is detected, a warning is issued, but the package distribution is still created.
  • To suppress warnings for near-matching provider names (e.g., 'Federal Office for Agriculture - FOAG' vs. 'Federal Office for Agriculture FOAG'), a similarity ratio can be used.

Customization Options

• --url: Allows to specify the STAC endpoint. By default, the command uses the service-stac endpoint (https://data.geo.admin.ch/api/stac/v0.9).
• --clear: Deletes all package distributions previously marked as managed by service-stac.
• --dry-run: Runs the command without making any changes, allowing you to preview the actions.

[msom]

@boecklic I'm not sure if introducing pystac-client is kind of an overkill here (see 8ec3478).