Rename `storeType` to `fetchType`, `FETCHONE` to `FETCH_ONE` to follow JDBC plugin pattern

[akeller]

Feature description

JDBC plugins follow a consistent pattern of using fetchType and fetchSize. In this plugin it looks like storeType is doing exactly what fetchType is doing, just with a different name. This should be consistent unless there is a technical reason why it's not.

FETCHONE should also be renamed to FETCH_ONE for consistency.

See https://kestra.io/plugins/plugin-gcp/bigquery/io.kestra.plugin.gcp.bigquery.query#properties_fetchType-body

[akeller]

Based on internal convo, this may be a bit more complex - https://kestra-io.slack.com/archives/C07KA8R1K0F/p1769450677481339