schedule immediately with module functions, don't wait
more flash-strings in the module and utility functions
support rare condition when body cannot be sent on connect, use poll to send it
don't wait for header line in body, and bail out when done parsing
make sure data is copied into the async variant, and remains there for
the duration of the connection
general async api is... more complicated that it needs to be
until wolfssl / brssl port is here, though, there is no other choice
secureclient config becomes a simple struct, pending further rework