FEEL context functions `get value` and `get entries` should support Java POJO as argument

Right now FEEL context functions `get value` and `get entries` support only Java Maps in context argument. An error is thrown if Java POJO is passed as parameter.

https://github.com/kiegroup/drools/blob/main/kie-dmn/kie-dmn-feel/src/main/java/org/kie/dmn/feel/runtime/functions/GetValueFunction.java#L34

Per Drools documentation a user-defined Java object is a valid context so it should be supported in all FEEL context functions.

For example the `context put` function allows the use Java POJO as context argument:
https://github.com/kiegroup/drools/blob/main/kie-dmn/kie-dmn-feel/src/main/java/org/kie/dmn/feel/runtime/functions/extended/ContextPutFunction.java#L98