Support for compression with webhook sources

Materialize webhook sources allow updates to be pushed to Materialize via HTTP POST, and now we've added support for compressed payloads.

Supported compression algorithms include:

To upload a compressed payload, include the Content-Encoding header with the appropriate compression algorithm:

Content-Encoding: br 
Content-Encoding: deflate 
Content-Encoding: gzip 
Content-Encoding: zstd 
 text

For more information about Materialize's webhook source, check out the quickstart page and the webhook reference page!