pybind/mgr: enhance CLICommand to fetch extra args from wrapped funcs

pybind/mgr: enhance CLICommand to fetch extra args from wrapped funcs

Previously, the CLICommand decorator "assumed" that the decorator was
applied directly to a mgr module api endpoint function. Now that we plan
on adding the Responder decorator into the mix we need a way of
properly fetching the arguments of the endpoint function. In addition,
the decorator itself needs to provide extra arguments to the mgr
(in cases where the endpoint function doesn't explicitly ask for it).
Thus we add a helper function to find the endpoint function when
wrapped as well as extract extra arguments when "walking" the stack
of __wrapped__ functions.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
(cherry picked from commit 2b22297f5664a2c778f6591dd1e1f3822fc5a3c1)