Including:
- add missing command for introspected doxygen
- run get_version.sh before running doxygen
- use find_package(Doxygen) to get the doxygen executable
- silence python and sqlite find_package warnings
- return cmake returncode if configuration fails
- require GTK3 3.22
- link all libraries to print-introspected-doxygen
- replace shell with use_shell for variable name
- revert wrong changes to propagation of return codes and add test
- disable pch when ccache is found
- make --enable-sudo a post-build step and a runtime option
- add docs subparser
- add enable-sudo option
- refactor positional argument values
- fix --check option and add shell option
- replace --no-task-lines with --quiet
- replace --nowaf with --no-build
- replace --run --run-no-build with run (--no-build)
- replace ns3 documentation related arguments with targets
- document test-ns3.py
- export include directories used by ns3 libraries
- refactor CMake documentation dependency checking and behavior
- add --allow-run-as-root for running MPI examples on the CI
