Add full text search on specified fields in the Okta integration.

[slawomirbabicz]

Feature Description Feature: Enable full text search on specified fields in the Okta integration. Fields that would be nice to have searchable using full text search:

okta.actor.display_name
okta.client.user_agent.raw_user_agent
okta.debug_context.debug_data.url

Motivation behind it is that those fields contain very relevant data, the log volume from Okta is quite low and there should be a way to give users a possiblity to search over that fields.

[elasticmachine]

Pinging @elastic/security-service-integrations (Team:Security-Service Integrations)