The script currently allows generating image test cases only using QEMU
VMs. As part of the process to allow using different approaches for
generating image test cases, introduce CLI commands using subparsers and
move the current functionality under 'qemu' command.
As part of extracting the generic parts from the TestCaseMatrixGenerator
class, rename it to QEMUTestCaseMatrixGenerator and move all generic
parts to a new BaseTestCaseMatrixGenerator class.
Change filtering options such as '--arch', '--distro', '--image-type'
to take only one argument and append the value to a list if used
multiple times, instead of accepting multiple values. This resolves an
issue of 'nargs=*' argument being too greedy and consuming command as
an additional argument.
Modify the script doc text to match the changes.
Signed-off-by: Tomas Hozza <thozza@redhat.com>
5be077e793