[GSS-RFE] Allow search in guided decision table for data from external datasource

The search feature in guided decision table (and dmn) has been available since rhpam/rhdm 7.5.0 per BAPL-1279.

However, the current search feature can only search the hard coded values,
for example: ['test 1', 'test2']

If the values are bound from external datasource, as documented in [1] "External data sources in enumerations", they are not able to be found from the search feature.
For example:
com.mycompany.DataHelper()).getListOfRegions()

Can we add the feature to be able to search the values bound from external datasource?

[1] https://access.redhat.com/documentation/en-us/red_hat_decision_manager/7.6/html-single/designing_a_decision_service_using_guided_decision_tables/index#enumerations-advanced-ref_guided-decision-tables

Testing

Automated test https://github.com/jboss-integration/bxms-qe-tests/pull/4041/files