Add support for the members api route located at extras/dynamic-groups/{id}/members

[tsm1th]

The members route is not currently supported at location extras/dynamic-groups/{id}/members. These detailed routes are handled via the DetailEndpoint method. The extras model does not currently support this detailed route.

Issue:

nb = pynautobot.api(url=NAUTOBOT_BASE_URL, token=NAUTOBOT_TOKEN)
nb.extras.dynamic_groups.get("my-group").members.list()
# AttributeError: object has no attribute "members"

Expected:

nb = pynautobot.api(url=NAUTOBOT_BASE_URL, token=NAUTOBOT_TOKEN)
nb.extras.dynamic_groups.get("my-group").members.list()
# <list output of members>