net/libngtcp2: Update to 1.2.0

* Switch to CMake for faster builds, it also additionally cleans up the
  port Makefile and removes the need for additional patching
* Disable OpenSSL requirement as it fails due to lack of QUIC support
  which is in 3.2
* Rearrange Makefile to follow Porters Handbook more closely and
  for readability

PR:		274782
Approved by:	portmgr (maintainer timeout 2+ weeks)