chore(engine-dmn): Adapt ScalaFeelEngine to New 1.7 feel-scala

[psavidis]

Notable points of this change:

Changes in feel-scala:

• 1.6.2 legacy behaviour: when disabling the var-args evaluation and a given function with arguments that do not exist throws an Exception
• 1.7.5 new behaviour: The above returns successfully and the answer contains suppressed failures.
• FeelEngine#evalExpression are deprecated and changed to the new FeelEngineApi#evaluateExpression. They also contain breaking changes in behaviour.

Change Reason:

• Adapt the behaviour of ScalaFeelEngine appropriately so that the legacy behaviour of ScalaFeelEngine is retained.

Breaking change:

• FeelExceptions with "no function found" messages now start with a capital letter.
• This is accepted as a small change to make the proxy code as simple as possible

Related-to: https://github.com/camunda/camunda-bpm-platform/issues/4100