Refactor NamespaceBehaviourWithListeners
There is quite a bit of confusion about what NamespaceBehaviour really
means inside yang-parser-reactor. This stems from the fact we actually
subclass NamespaceBehaviour and forward calls to a delegate in
NamespaceBehaviourWithListeners.
Refactor the class hierarchy, by renaming
NamespaceBehaviourWithListeners to NamespaceAccess, introducing explicit
access methods. These are then realized by a dedicated subclass,
BehaviourNamespaceAccess.
This provides a clear separation of concerns, also removing the need
to verify objects in ReactorStmtCtx.
JIRA: YANGTOOLS-1204
Change-Id: Ie6334e8a20359c0faf73a2150541f06f55cdd083
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>