Ensure all the variables are initialized when running the main function
of isctest module. This enables proper environment variables during test
script development when only conf.sh is sourced, rather than the script
being executed by the pytest runner.
Initializing the conftest logging upon importing the isctest package
isn't practical when there are standalone pieces which can be used
outside of the testing framework, such as the asyncdnsserver module.
Unify the different loggers (conftest, module, test) into a single
interface. Remove the need to select the proper logger by automatically
selecting the most-specific logger currently available.
This also removes the need to use the logger/mlogger fixtures manually
and pass these around. This was especially annoying and unwieldy when
splitting the test cases into functions, because logger had to always be
passed around. Instead, it is now possible to use the
isctest.log.(debug,info,warning,error) functions.