add PubsubToPubsub Masking secret columns from pub/sub secret attribute keys

[case-k-git]

add PubsubToPubsubMaskedEventKeyValue template masking secret value from pub/sub secret attribute keys.

mvn -Pdataflow-runner compile exec:java \
  -Dexec.mainClass=com.google.cloud.teleport.templates.PubsubToPubsubMaskedEventKeyValue \
  -Dexec.args="--project=''
              --tempLocation='' \
              --templateLocation=gs://beam-test-kinesis/templates/PubsubToPubsubMaskedEventKeyValue \
              --experiments=enable_stackdriver_agent_metrics \
              --enableStreamingEngine \
              --runner=DataflowRunner \
              --maskedAttributeKey=secret_columns \
             --maskedEventKeyValue=null \
              --region=us-central1"

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bvolpato]

Hi @case-k-git -- thanks for your contribution here. Unfortunately we ran behind on reviews, and the structure of the project changed a bit. Is there still interest in pursuing this template? We can work together on a plan to resolve conflicts + review the code.