* Store session data sent from Enterprise Search server
This modifies the EnterpriseSearchRequestHandler to remove any data in a
response under the _sessionData key and instead persist it on the server
side.
Ultimately, this data will be persisted in the login session, but for
now we'll just store it in a cookie. https://github.com/elastic/kibana/issues/92558
Also uses this functionality to persist Workplace Search's OAuth token
package.
* Only return a modified response body if _sessionData was found
The destructuring I'm doing to remove _sessionData from the response is
breaking routes that currently expect an empty response body. This
change just leaves those response bodies alone.
* Refactor from initial feedback & add tests
* Decrease levity
* Changes from PR feedback
Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>