api: add resource map api endpoints for PCI and USB

api: add resource map api endpoints for PCI and USB

this adds the typical section config crud API calls for
USB and PCI resource mapping to /cluster/mapping/{TYPE}

the only special thing that this series does is the list call
for both has a special 'check-node' parameter that uses the
'proxyto_callback' to reroute the api call to the given node
so that it can check the validity of the mapping for that node

in the future when we e.g. broadcast the lspci output via pmxcfs
we drop the proxyto_callback and directly use the info from
pmxcfs (or we drop the parameter and always check all nodes)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>