Add support for Okta Identity Engine while fetching policies (#126)

[misraved]

Example query results

Results

``` Add example SQL query results here (please include the input queries as well) ```

[ParthaI]

FYI: The review comments provided in the original PR need to be addressed. Ref: https://github.com/turbot/steampipe-plugin-okta/pull/126#pullrequestreview-2088880335

[misraved]

@ParthaI notes for the PR:

• Why are we adding a new config argument engine_type? Does Terraform handle it similarly?
• Can the engine_type config argument be specified by an environment variable?
• Can we add new tables for the tables that would need a new engine type? Since the API structure differs, I am more inclined to add the new tables.

[misraved]

Addressed in https://github.com/turbot/steampipe-plugin-okta/pull/139