Task/581 v1 context entities attributes 4ops

### Description
Four new conv ops:
GET/PUT/POST/DELETE /v1/contextEntities/type/TYPE/id/ID/attributes/ATTR_NAME

Well, related it is.
The same serviceRoutine is used for PUT /v1/contextEntities/type/TYPE/id/ID/attributes/ATTRIBUTE_NAME and
PUT /v1/contextEntities/ID/attributes/ATTRIBUTE_NAME.

A bug was found and fixed for PUT /v1/contextEntities/ID/attributes/ATTRIBUTE_NAME and it got automatically fixed for its 'brother service 'PUT /v1/contextEntities/ID/attributes/ATTRIBUTE_NAME'