Fix compression chaining with vector interceptor

[dkropachev]

Summary

• Make request gzip compression cache compressed bytes before the AWS SDK asks for the content body, so headers and body stay consistent when vector request rewriting runs first.
• Add regression coverage for vector-before-gzip request ordering and response decompression before vector response parsing.
• Keep this stacked on vector-1 because the tests depend on vector-search support added there.

Base

• Stacked on vector-1 / Add Alternator vector search support #145.

Tests

• JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64 PATH=/usr/lib/jvm/java-11-openjdk-amd64/bin:$PATH mvn -q fmt:check
• JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64 PATH=/usr/lib/jvm/java-11-openjdk-amd64/bin:$PATH mvn -q -Dtest=VectorSearchInterceptorTest,VectorSearchHttpInterceptorTest,GzipRequestInterceptorTest,ResponseCompressionInterceptorTest test

[dkropachev]

Folded into #145 as part of the squashed review fixes.