This commit adds a new argument `provider` to the iosxr shared module that
allows common connection parameters to be passed as a dict object. The
constraints on the args still applies. This commit also updates the iosxr
doc fragment.
This commit adds a new shared module for working with Cisco IOS XR devices over
CLI (SSH). It also provides a documentation fragement for the commmon arguments
provided by the iosxr module.
