Changes to Get thread subscriptions

api operation id get-rooms-roomId-threads-threadId-subscriptions removed and replaced with get-thread-subscriptions

the response property data became required for the status 200

the response property data/items/allOf[subschema #1: Subscription]/createdAt became required for the status 200

the response property data/items/allOf[subschema #1: Subscription]/kind became required for the status 200

the response property data/items/allOf[subschema #1: Subscription]/subjectId became required for the status 200

endpoint added