Arthur Churchill

Could we add `SchemaUpdateOption` param to BQ WriteParam?

1

**CONTEXT** We are trying to use [saveAsBigQueryTable](https://github.com/spotify/scio/blob/edb07ff5904e8f9116aa78eeaee7b9e1a0f36d4a/scio-google-cloud-platform/src/main/scala/com/spotify/scio/bigquery/syntax/SCollectionSyntax.scala#L60) to append data to a table where additional fields might be added to the schema. At the moment, we are unable to do...