Basic test for streams multiplexing: 1. Different HTTP/2 requests (i.e. HEADERS/CONTINUATION/DATA frames in each request) are sent in several streams - one by one, without waiting the responses; 2. And correct HTTP/2 responses must be received for each request/stream (regardless of the sending/receiving order). Do this in one and several TCP connections in parallel.
New tests:
Added env variable for curl secrets.