* 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.
* Mention PostgreSQL in sql_database_instance docs
As mentioned in hashicorp/terraform#12617 the
google_sql_database_instance resource already supports `POSTGRES_9_6` as
`database_version`, it is just undocumented so far.
* Make naming of google_sql_database consistent
Looks like this is a relict from some copy & paste from
`google_storage_*` while writing the docs for `google_sql_database`.
* Note that Postgres support is still BETA