chore: Migrate all synth.py scripts from artman to bazel

[vam-google]

This change depends on a pending change in googleapis repository and a pending change in synthtool googleapis/synthtool#459.

All the migrated synth.py scripts were tested with the following results:

Client Name (subfodler)	Generator	Comments
Asset	Bazel
AutoMl	Bazel	With fix in service.yaml
BigQuery	N/A
BigQueryDataTransfer	Bazel	Experimental annotation for methods removed
Bigtable	Bazel	With BigTable -> Bigtable case fix in synth.py
Billing	Bazel
CommonProtos	N/A
Container	Bazel
Core	N/A
Dataproc	Bazel	Lots of changes, seems like current ones are still from gapic_yaml v1
Datastore	Bazel	Retry Params are like in gapic_yaml_legacy
Debugger	Bazel
dev	N/A
Dialogflow	Bazel	google.longrunning.Operations is missing in *clieng_config.php files, but same is true for artman
Dlp	Bazel	Abunch of breaking changes, but same is for artman
docs	N/A
ErrorReporting	Bazel
Firestore	Bazel
Iot	Bazel	License year in the client classe is changed from 2018 to 2020
Kms	Bazel	Bethods like cryptoKeyPathName are removed, but same is for artman
Language	Bazel	Some comments changes, look safe
Logging	Bazel	Lots of breaking changes, but same with artman
Monitoring	Bazel
OsLogin	Bazel	Experimental tag removed, but same with artman
PubSub	Bazel	Some resource names changes, but same with artman
Recommender	Bazel
Redis	Bazel
Scheduler	Bazel	V1beta1 case bug fix, and related changes in V1beta1 package
SecretManager	Bazel	Comments changes, but look safe
SecurityCenter	Bazel	Service yaml fix, plus some additions, plus SecurityCenter Securitycenter case fix in synth.py
ServiceDirectory	Bazel
Spanner	Bazel	Fixed missing r'' fix in synth.py for replacements
Speech	Bazel	Experimental removed from client class, but same with artman
src	N/A
Storage	N/A
Talent	Bazel	Breaking changes, but same with artman
Tasks	Bazel
tests	N/A
TextToSpeech	Bazel
Trace	Bazel
Translate	Bazel
VideoIntelligence	Bazel	Required change in BUILD.bazel file to use legacy gapic for v1
Vision	Bazel
WebRisk	Bazel	WebRisk -> Webrisk case fix for GPBMetadata path
WebSecurityScanner	Bazel

[vam-google]

@dwsupplee PTAL

[vam-google]

@dwsupplee Thanks for reviewing it!
How can we merge this now? Should I do it myself somehow, or wait for Yoshi to do it?

[dwsupplee]

All set :).