Add aci_system_connectivity_prefs module

[dneilan-intel]

A new module has been added to facilitate reading and mutating a fabric's management connectivity preference (inband/out-of-band)

APIC Connectivity Preferences is a fabric-wide system setting which can set to either in-band or out-of-band communication.

Tests have been added to verify this setting can be read and updated

[lhercot]

Thanks for your contribution!