Describe the change
This allows, but does not require, a client to use GZIP compression when calling Strelka.

Originally implemented in sublime-security#26

Describe testing procedures

	opts := []grpc.CallOption{grpc.WaitForReady(true), grpc.UseCompressor(grpcgzip.Name)}
	scanFile, err := sc.frontend.ScanFile(ctx, opts...)

I modified a client to include the grpc.UseCompressor(grpcgzip.Name) option and validated that grpc: Decompressor is not installed for grpc-encoding "gzip" is returned without this change. Everything works as normal when this change is included. I also tested without the option to ensure backwards compatibility.

Sample output
No changes.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of and tested my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings