feat: native Snowflake bulk unload for `BATCH` messages

[aaronsteers]

Related:

• SDK BATCH docs: https://meltano-sdk--904.org.readthedocs.build/en/904/batch.html
• Snowflake COPY INTO docs: https://docs.snowflake.com/en/user-guide/data-load-local-file-system.html
• Corresponding feature on tap-snowflake: https://github.com/MeltanoLabs/target-snowflake/issues/1

Spec details:

1. Use table stages to avoid requiring S3 creds.
2. Use default encoding of jsonl and gzip to match initial built-in SDK feature spec.
3. Skip record validation to avoid needing to parse the raw files.
4. One BATCH message and manifest per COPY command. (Watch COPY command will contain multiple files.)

[aaronsteers]

cc @edgarrmondragon