Add plugin support for Metabase 0.35.x

[sadjunky]

I've been encountering the following error when using the plugin with Metabase 0.35.x:

No method in multimethod 'execute-reducible-query' for dispatch value: :bigquery_alt

The plugin works fine for 0.34.x.

[kaustavdm]

This issue seems to be caused by a breaking change Metabase introduced for database drivers.

The bigquery driver in metabase has added defmethod driver/execute-reducible-query