Using this as the top level issue for tracking the addition of synth scripts to our gapic libraries.

• update gax and synth.py nodejs-bigquery-data-transfer#43
• Add synth.py and update google-gax nodejs-bigtable#211
• Add synth.py and update google-gax nodejs-cloud-container#37
• feat: add a synth file, regenerate nodejs-dataproc#35
• Add synth.py and update google-gax nodejs-datastore#116
• feat: add synth script and regenerate nodejs-dlp#70
• Add synth.py and update google-gax nodejs-firestore#221
• Add synth script and update google-gax nodejs-language#63
• Create synth script for nodejs-logging nodejs-logging#127
• Add synth.py and update google-gax nodejs-monitoring#59
• Add synth.py and update google-gax nodejs-os-login#33
• Add synth script and update gax-google nodejs-pubsub#151
• update gax and add synth.py nodejs-redis#11
• add synth.py and generate nodejs-spanner#244
• Add synth.py and update google-gax nodejs-speech#94
• synth script checkin nodejs-tasks#12
• Re-generate v1beta1 and check in synth tool nodejs-text-to-speech#27
• Add synth.py and update google-gax nodejs-video-intelligence#48
• Create synth script and regenerate v1 nodejs-vision#78

After we're done here, lets go get these added to the kokoro job for autosynth.