src: move header inclusion out of namespace

The placement of a previous fix to include proper size_t types in
addons was erroneously placed inside a namespace, move to just before.

Fix #6992
test: delete invalid http test

The test is no longer valid for the original scenario.

It now fails intermittently because of two other issues:
1. Since the client is only processing one readable event, the
   client request is not enough to keep the process alive and the
   process can exit before the desired events have been raised.
2. Reading just 1 byte is not enough to guarantee that the parser
   will eventually consume all the data and raise the desired
   parse error. I tried postponing the server.close() to address
   the issue at [1], but then the test just hangs sometimes.
zlib: add sync versions for convenience methods
De-dupe After and make a separate method
Fix docs
Correct last nits
de-dupe writing function
remove callbacks