Fixed validation of resource-assignment-params.config-assign

Fixed validation of resource-assignment-params.config-assign

- In order to preserve the validation of the whole BPP response, I added a
  normalization step that will convert any non-JSON part of the response
  into a JSON-equivalent representation.
  This normalization is carried out by the JSLT library that provides many
  JSON manipulations using a JSON-like specification.
  See https://github.com/schibsted/jslt for more details.

- Fix UAT not being run by maven
  The Surefire plugin does accept '*Tests.java' but DOESN'T '*Tests.kt'!
  The UAT test class was renamed to use the 'Test' suffix only.

- Improved maintainability of UAT-Engine by switching from explicitly field
  handling to POJO-based parsing using Jackson along with SnakeYaml.
  UAT-related POJOs created on new module UatDefinition.kt

- Added a Protobuf-like description of an UAT YAML document.

Change-Id: Id1178489caa4e97808747a99bc9324fc84e9b96e
Issue-ID: CCSDK-1620
Signed-off-by: ebo <eliezio.oliveira@est.tech>