Add BigQuery support

[lidalei]

This PR adds BigQuery support to flyway. A sample configuration file is

# Long properties can be split over multiple lines by ending each line with a backslash
flyway.locations=filesystem:<path_to_sql_folder>

flyway.url=jdbc:bigquery:https://https://www.googleapis.com/bigquery/v2:443;ProjectId=<gcp_project_id>;Location=EU;OAuthType=0;OAuthServiceAcctEmail=<sa_name>@<gcp_project_id>.iam.gserviceaccount.com;OAuthPvtKeyPath=<path_to_service_account_key_file.json>;
flyway.user='hello'
flyway.password='world'

flyway.driver=com.simba.googlebigquery.jdbc42.Driver
flyway.jarDirs=<path_enclosing_simba_driver>/SimbaJDBCDriverforGoogleBigQuery42_1.2.16.1020

flyway.schemas=flyway
# The simba JDBC driver always creates schema in the US multi-region (doesn't respect the BigQuery Location configuration).
# So we have to manually create the schema and tell flyway to not create schema.
# Please ignore the warning flyway outputs if you have created the schema in the Location.
flyway.createSchemas=false

It supports both versioned and repeatable migrations. The driver can be obtained via Google Cloud. Note BigQuery's limitations in transactional support.

[CLAassistant]

All committers have signed the CLA.

[DoodleBobBuffPants]

Thanks for the PR! BigQuery support has now been merged and will be available from the next release. To find out more about how to begin using Flyway with BigQuery, visit https://flywaydb.org/documentation/database/big-query