Pluggable interface version negotiation.
Like the EntryPoint, this mechanism allows for the host to negotiate with the Pluggable for its interface version. If the pluggable does not support an interface between the two ranges (inclusive), it should return UNSUPPORTED_INTERFACE.
Note that this is not a negotiation of the SPIT interface versions (which is the responsibility of EntryPoint. Rather, each extension point is expected to version its own cluster of interfaces. It is that interface version that is being negotiated here.
negotiate_interfaces can be used to implement this method.
|min_host_interface||The host's minimum supported interface version number for this Pluggable's intended extension point.|
|max_host_interface||The host's maximum supported interface version number for this Pluggable's intended extension point.|
|The version number supported by the host and the Pluggable or UNSUPPORTED_INTERFACE.|