tests: introduce new test for compression

test are trying both algorithems (snappy, lz4), while
counting the size of the frames coming into scylla

for reference we also have one test doing the same without
compression

test main structure was borrowed from java-driver, the usage
of proxy to count the packets is unique to this change.

scylla/tests/integration/main.rs

@@ -18,4 +18,5 @@ mod silent_prepare_batch;
 mod silent_prepare_query;
 mod skip_metadata_optimization;
 mod tablets;
+mod compression;
 pub(crate) mod utils;