[google|sql] Add support for Flags

- Add models, requests and tests for Flags
[google|sql] Add support for Operations

- Add models, requests and tests for Operations
[google|sql] Add support for Instances

- Add models, requests and tests for Instances
[google|sql] Add support for SslCerts

- Add models, requests and tests for SslCerts
[google|sql] Add support for BackupRuns

- Add models and requests for BackupRuns
[google|sql] Add examples
[dynect|dns] Let job_poll_timeout be specified.
[google|compute] Refactor Compute to use the new Shared module

Commit d801b27 introduced a new Shared module with logic to initialize
a google_client_api and to make requests.

This commit refactors Compute to use the new Shared module.
Merge pull request #3081 from dpiddy/dynect-dns-specify-job-poll-timeout

[dynect|dns] Let job_poll_timeout be specified.
Merge pull request #3080 from frodenas/gce_shared

[google|compute] Refactor Compute to use the new Shared module
Merge pull request #3077 from frodenas/gce_sql

[google|sql] Complete support for Google Cloud SQL