Add missing dependencies used in java-docs-samples

[kweinmeister]

The following libraries are still referenced by version in GoogleCloudPlatform/java-docs-samples.

The request is to add any of these that would be appropriate to libraries-bom. Note that there may be other missing artifacts in the same family, e.g. Spanner, that may also belong, but aren't referenced in the sample repo.

com.google.cloud

com.google.cloud:google-cloudevent-types
com.google.cloud:cloud-spanner-r2dbc
com.google.cloud:cloud-spanner-spring-data-r2dbc

com.google.cloud.*

com.google.cloud.bigtable:bigtable-hbase-1.x
com.google.cloud.bigtable:bigtable-hbase-beam

com.google.cloud.functions:functions-framework-api
com.google.cloud.functions.invoker:java-function-invoker

com.google.cloud.sql:cloud-sql-connector-r2dbc-mysql
com.google.cloud.sql:cloud-sql-connector-r2dbc-postgres
com.google.cloud.sql:cloud-sql-connector-jdbc-sqlserver
com.google.cloud.sql:mysql-socket-factory-connector-j-6
com.google.cloud.sql:mysql-socket-factory-connector-j-8
com.google.cloud.sql:postgres-socket-factory

[patricklucas]

Hit this today, getting a Guava version conflict from including both the latest version of postgres-socket-factory along with the Cloud Storage SDK whose version was set by a few-months-old version of the BOM.

   > Could not resolve com.google.guava:guava:31.1-jre.
     Required by:
         project :xxx > com.google.cloud:libraries-bom:26.14.0
         project :xxx > com.google.cloud:google-cloud-storage:2.22.1
         project :xxx > com.google.cloud:google-cloud-storage:2.22.1 > com.google.api-client:google-api-client:2.2.0
      > Module 'com.google.guava:guava' has been rejected:
           Cannot select module with conflict on capability 'com.google.guava:listenablefuture:1.0' also provided by [com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava(runtime)]
   > Could not resolve com.google.guava:guava:32.1.1-android.
     Required by:
         project :xxx > com.google.cloud.sql:postgres-socket-factory:1.13.0
         project :xxx > com.google.cloud.sql:postgres-socket-factory:1.13.0 > com.google.cloud.sql:jdbc-socket-factory-core:1.13.0
      > Module 'com.google.guava:guava' has been rejected:
           Cannot select module with conflict on capability 'com.google.guava:listenablefuture:1.0' also provided by [com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava(runtime)]