Move most of the code out of .btm files

[yurishkuro]

i.e. below is way too much code to put there, it can be moved into some helper class where code can be checked at compile time and unit tested.

associateSpan($0, getTracer().buildSpan($0.getRequestMethod())
.withTag(io.opentracing.tag.Tags.SPAN_KIND.getKey(), io.opentracing.tag.Tags.SPAN_KIND_CLIENT)
 +    .withTag(io.opentracing.tag.Tags.HTTP_URL.getKey(), $0.getURL().toString())
 +    .withTag("http.query", $0.getURL().getQuery())
 +    .asChildOf(currentSpan())
 +    .start());
 +  getTracer().inject(retrieveSpan($0).context(), io.opentracing.propagation.Format$Builtin.HTTP_HEADERS,
 +    new io.opentracing.contrib.agent.jnet.propagation.HttpURLConnectionInjectAdapter($0));