[Improvement] Add Originating Exception Message When An `TemplateSyntaxException` Is Thrown As A Result Of Function Invocation Error

[bhreinb]

When an invocation to a function happens which fails it is caught as either a
IllegalAccessException or InvocationTargetException within jinjava.de.odysseus.el.tree.impl.ast#eval
which is re-thrown as an ELException .

This ELException exception gets caught in class com.hubspot.jinjava.el.ExpressionResolver#resolveExpression which ultimately gets caught again and gets re-thrown as a TemplateSyntaxException via line 188

      } else {
        interpreter.addError(
          TemplateError.fromException(
            new TemplateSyntaxException(
              expression,
              e.getMessage(),
              interpreter.getLineNumber(),
              e
            )
          )
        );
      }

It would be nice if the TemplateSyntaxException included the original exception message that caused the problem perhaps. Namely

      } else {
        interpreter.addError(
          TemplateError.fromException(
            new TemplateSyntaxException(
              expression,
              String.format("%s%nOriginal Failure:%n%s" e.getMessage(), e.getCause().getMessage())
              interpreter.getLineNumber(),
              e
            )
          )
        );
      }

[bhreinb]

Resolved by this PR #753