Remove obsolete qmp class

[abbbi]

The qemu agent client still uses the qmp class as shipped, it should be possible to use qemu.qmp library for the agent communication, too. negotiate option must be set to false, ..

[abbbi]

Current qemu.qmp implementation has troubles with older qemu agents, the execute() function might hang forever
if the qemu agent does not support the qmp execution IDs:

https://gitlab.com/jsnow/qemu/-/issues/62

only way would be to use the not exposed ._raw() function with assign_id=False, but i think ill just wait until
qemu.qmp is fixed in that regard.

[jnsnow]

working on it, apologize for the slowness here. There's a bit of work to do in order to extract the library out from qemu.git so that patches can be contributed faster and more smoothly.