Add support for BATCH type messages as described in Meltano SDK documentation

[VMois]

Is your feature request related to a problem? Please describe.
The feature request is not linked to any specific issue. The current Singer-IO specification exchanges messages between taps and targets one by one using JSON. If the target supports the bulk load, it would be more efficient to leverage that.

Describe the solution you'd like
Meltano SDK provides a possible solution by introducing a new type of message - BATCH (currently in preview). Instead of sending individual messages, BATCH messages sends a list of files, and then using a temporary filesystem (local or S3) target can load the data in bulk.

Describe alternatives you've considered
I haven't considered any other alternatives except Meltano SDK BATCH messages.

Additional context
This is a minor feature. I wanted to discuss the possibility of implementing support for the BATCH type.