Establish the TLS connection with the client earlier

Establish the TLS connection with the client earlier

... and decide how to route the request afterwards.

This allows to change the forwarding settings based
on information from the https-inspected request,
for example the path.

Adjust build_request_line() to create a CONNECT
request line when https-inspecting and forwarding
to a HTTP proxy.

Fixes SF bug #925 reported by Wen Yue.