Add a main() function to linters.py so that the Python CI infrastructure
has something it can run.
Now, linters.py represents an invocation of the linting scripts that
more resembles a "normal" execution of pylint/mypy, like you'd expect to
use if 'qemu' was a bona-fide package you obtained from PyPI.
297, by contrast, now represents the iotests-specific configuration bits
you need to get it to function correctly as a part of iotests, and with
'qemu' as a namespace package that isn't "installed" to the current
environment, but just lives elsewhere in our source tree.
By doing this, we will able to run the same linting configuration from
the Python CI tests without calling iotest logging functions or messing
around with PYTHONPATH / MYPYPATH.
iotest 297 continues to operate in a standalone fashion for now --
presumably, it's convenient for block maintainers and contributors to
run in this manner.
See the following commit for how this is used from the Python packaging side.
Signed-off-by: John Snow<jsnow@redhat.com>