* Add charset and collation to google_sql_database.
* Add documentation for charset, collation attributes.
* Extend the existing acceptance test to also cover charset and collation.
* Charset and collation always have a value present. Also inline.
* Move charset and collation to optional arguments.
* Add charset and collection to the example.
* Document charset and collation defaults.
* Keep TestAccGoogleSqlDatabase_basic as is, add TestAccGoogleSqlDatabase_update.