[kie-issues#1841] Date and time related functions as non literal not permitted

[yesamer]

Closes apache/incubator-kie-issues#1841

According to the DMN 1.6 Specs:

In this PR:

• In case of Endpoints of FunctionInvocation type, only the functions type are allowed
• The above function type are allowed as literal only (e.g they can't have functions as parameters)
• Updated Tests accordingly
• Allowed node type, values and function are now stored as Set, that is a better fit for this use case.

[Copilot]

Pull Request Overview

This PR enforces DMN 1.6 rules for range endpoints by allowing only date/time built‐in functions (without nested calls) or literals, and updates tests accordingly.

• Introduces isAllowedFunctionInvocationNode to restrict FunctionInvocationNode endpoints
• Refactors ALLOWED_NODES and ALLOWED_TYPES to use Set and updates RangeFunction logic
• Revises RangeFunctionTest data and assertions to cover date/time functions and literals

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
kie-dmn-feel/src/main/java/org/kie/dmn/feel/runtime/functions/RangeFunction.java	Adds isAllowedFunctionInvocationNode, switches allowed node/type lists to sets, refactors parsing logic
kie-dmn-feel/src/test/java/org/kie/dmn/feel/runtime/functions/RangeFunctionTest.java	Updates test cases for valid/invalid endpoints, refactors test data arrays

Comments suppressed due to low confidence (1)

kie-dmn/kie-dmn-feel/src/test/java/org/kie/dmn/feel/runtime/functions/RangeFunctionTest.java:565

• Syntax error: the second string literal is missing a closing parenthesis and quote. It should be "duration(\"P2Y6M\")".

                {"duration(\"P1Y6M\")", "duration(\"P2Y6M\""},

[gitgabrio]

Thx - LGTM!