This pull request introduces HTTP response compression to Alternator, allowing responses (both string and chunked) to be compressed using `gzip` or `deflate` when requested by clients and when the response size exceeds configurable thresholds.
* Added new source files `http_compression.cc` and `http_compression.hh` implementing compression logic, including parsing client `Accept-Encoding` headers, selecting compression algorithms, and compressing response bodies using zlib.
* Added two new configuration options to `db::config` (`alternator_response_gzip_compression_level` and `alternator_response_gzip_compression_threshold_in_bytes`) to control compression level (and optionally disable compression with level 0 - no compression) and minimum response size for compression.
* Added tests showing compliance with DynamoDB behavior.
Fixes#27246
New feature - no backporting
Closesscylladb/scylladb#27454
* github.com:scylladb/scylladb:
alternator/http_compression: Add compression of streamed response
alternator/http_compression: Add implementation od gzip/deflate of string response
alternator/http_compression: Add handling of Accept-Encoding header
test/alternator: add tests for compressed responses
5f79d93102