Providing reserved keyword support for `fivetran_utils.add_passthrough_columns()`

[fivetran-avinash]

Currently, we have trouble bringing through reserved keywords using the add_passthrough_columns macro.

This issue was surfaced from an attempt to bring through the group field in the entity source table in Netsuite2, as it treats group as if it should be used in a group by statement.

Error message:

Syntax error: Expected keyword BY but got keyword AS at [373:2]
  compiled Code at target/run/netsuite_source/models/netsuite2/stg_netsuite2__entities.sql

See this Height ticket.