python: create qemu packages

move python/qemu/*.py to python/qemu/[machine, qmp, utils]/*.py and
update import directives across the tree.

This is done to create a PEP420 namespace package, in which we may
create subpackages. To do this, the namespace directory ("qemu") should
not have any modules in it. Those files will go into new 'machine',
'qmp' and 'utils' subpackages instead.

Implement machine/__init__.py making the top-level classes and functions
from its various modules available directly inside the package. Change
qmp.py to qmp/__init__.py similarly, such that all of the useful QMP
library classes are available directly from "qemu.qmp" instead of
"qemu.qmp.qmp".

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-10-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

tests/qemu-iotests/300

@@ -28,7 +28,7 @@ import iotests
 
 # Import qemu after iotests.py has amended sys.path
 # pylint: disable=wrong-import-order
-import qemu
+from qemu.machine import machine
 
 BlockBitmapMapping = List[Dict[str, object]]
 
@@ -466,7 +466,7 @@ class TestBlockBitmapMappingErrors(TestDirtyBitmapMigration):
         # the failed migration
         try:
             self.vm_b.shutdown()
-        except qemu.machine.AbnormalShutdown:
+        except machine.AbnormalShutdown:
             pass
 
     def test_aliased_bitmap_name_too_long(self) -> None:

tests/qemu-iotests/iotests.py

@@ -38,7 +38,7 @@ from contextlib import contextmanager
 
 # pylint: disable=import-error, wrong-import-position
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
-from qemu import qtest
+from qemu.machine import qtest
 from qemu.qmp import QMPMessage
 
 # Use this logger for logging messages directly from the iotests module