Migrate Indexer Service to Anthos (GONRG-4090)

NOTICE

devops/gcp/configmap/templates/indexer-variables.yml

devops/gcp/configmap/values.yaml

provider/indexer-gcp/README.md

provider/indexer-gcp/docs/anthos/README.md

provider/indexer-gcp/docs/anthos/pics/client.png

provider/indexer-gcp/docs/anthos/pics/rabbit.PNG

provider/indexer-gcp/docs/anthos/pics/sa.png

provider/indexer-gcp/docs/gcp/README.md

provider/indexer-gcp/pom.xml

...pengroup/osdu/indexer/cache/DatastoreCredentialCache.java

...opengroup/osdu/indexer/cache/ElasticCredentialsCache.java

...oup/osdu/indexer/di/DatastoreCredentialsCacheFactory.java

...va/org/opengroup/osdu/indexer/di/ElasticSearchConfig.java

...osdu/indexer/di/ElasticSearchConfigurationProperties.java

...rg/opengroup/osdu/indexer/di/PubSubExtensionsFactory.java

...a/org/opengroup/osdu/indexer/di/TenantFactoryService.java

.../opengroup/osdu/indexer/persistence/DatastoreFactory.java

.../osdu/indexer/persistence/ElasticRepositoryDatastore.java

...ava/org/opengroup/osdu/indexer/publish/PublisherImpl.java