Merge branch 'notification-rework' into 'master'

NOTICE

provider/notification-gc/docs/anthos/README.md

provider/notification-gc/docs/gc/README.md

...der/notification-gc/docs/gc/pics/notification-classes.png

provider/notification-gc/docs/gc/pics/notification.png

provider/notification-gc/pom.xml

...up/osdu/notification/provider/gcp/config/CacheConfig.java

...sdu/notification/provider/gcp/config/RedisProperties.java

...ation/provider/gcp/config/ScopeModifierPostProcessor.java

...ion/provider/gcp/config/SubscriptionAPIConfigFactory.java

...otification/provider/gcp/model/ExternalSubscriptions.java

...ification/provider/gcp/pubsub/OqmNotificationHandler.java

...otification/provider/gcp/pubsub/OqmSubscriberManager.java

...ification/provider/gcp/pubsub/OqmSubscriptionHandler.java

...fication/provider/gcp/pubsub/OqmSubscriptionProvider.java

...ification/provider/gcp/pubsub/PubsubHandshakeHandler.java

...ation/provider/gcp/pubsub/PubsubRequestBodyExtractor.java

...ification/provider/gcp/pubsub/di/OqmSignatureService.java

...n/provider/gcp/pubsub/di/OqmSubscriptionCacheFactory.java

...cation/provider/gcp/pubsub/di/OqmSubscriptionHandler.java