port to Ubuntu 22.04

close #50 (closed)

This MR is composed of various minor fixes and updates:

• 📝 add doc for build and install for Ubuntu 22.04
• 👷 add build Docker image for dependencies in Ubuntu 22.04, and build debian package for ubuntu 22.04
• 👷 add 22.04 into CI
• 👷 updated runtime deps for ubuntu 22.04
• 🔧 add a cmake option for Switcher IO, and remove forced installation of python dependencies
• 🐛 remove deprecated and useless call to PyEval_InitThreads
• 🐛 fix deprecated calls to loop related methods in python async io
• 🐛 fix pyquid session segfault
• 🐛 shmshot: do not quit in callback
• 🐛 fix cmake for 22.04
• 🐛 fix gst_element_get_request_pad not available after gstreamer version 1.20

Several ongoing works will need to be enabled in Switcher for Ubuntu 22.04 when completed. They currently fail:

• 👷 disable build and test of WEBRTC plugin and SWITCHERIO for Ubuntu 22.04