I understand that in order to enable the connectivity to BigQuery to Jaspersoft iReport Designer, a plugin was needed to be installed. However, how would one do the same for Jaspersoft Studio?
You will need to create a data Adapter in Jaspersoft Studio to access Google Big Query.
But since Google Big Query has come a long way since the connector was built, I will probably try a JDBC driver first, check this one https://code.google.com/p/starschema-bigquery-jdbc/wiki/BigQuery
I have not tried but I do not see why it would not work. Just add the driver to the standard JSS JDBC data adapter.