* implement functions to append/get metadata and set/get status code
* сhanged behavior to return nil instead of empty metadata for getResponseMetadata()
* сhanged work with HTTP headers to use direct array assignment instead of for-range
* fix linters
* fix meter handler
* fix uninitialized response metadata for incoming context
* removed a useless test
* metrics handler has been fixed to work with compressed data
pugnack
545e372b82