Add compression to elasticsearch output

[cookieshake]

Hello. I need a client-side compression for elasticsearch output, so I implemented this.

I did make test, make fmt, make lint.

I am using this commit in my service, and it seems it works well.

[cookieshake]

I saw that the test failed. I read the contribution guideline again, and did make docs. Now I am running make test-integration but it fails. So I am investigating the cause.

[mihaitodor]

Hi @cookieshake and thank you for the contribution! I don't see anything in there that could make the integration tests fail, so it could just be a flakey test, but I'll let @Jeffail confirm.

[Jeffail]

Hey @cookieshake, looks good but I think it's worth naming the field gzip_compression to be more explicit. Is the integration test specifically failing for elasticsearch? Because like @mihaitodor said there's some flakiness in there 😅

[Jeffail]

Thanks @cookieshake, looks good!

[cookieshake]

@mihaitodor thank you for checking my code!

@Jeffail I changed compression to gzip_compression. The integration test failed because the dockerd of my pc was not working properly. I did the test on another ubuntu VM, and the test for output/writer was successful. But other tests like mssql test failed. Thank you for checking & merging!