Draft: Resolve "Add capacity to push multiple items at once"

Add method StacTransactionHandler.publish_bulk_items to handle the publication of a list of items by chunks of multiple items.

Useful references:

• the swagger: https://api.stac.teledetection.fr/api.html
• bulk transaction description: https://stac-utils.github.io/stac-fastapi/api/stac_fastapi/extensions/third_party/bulk_transactions/#stac_fastapi.extensions.third_party.bulk_transactions.BulkTransactionExtension

Closes #15