Add get attribute type function in utils

[romanodanilo]

Description

While testing with the xosc examples, it was found a case in which an OpenSCENARIO expression was considered a parameter, and for that an issue was incorrectly raised:

        Error:      #0: Issue flagging when used parameters is not defined or has not default value within a catalog
                    Parameter value {250/3.6} for attribute maxSpeed is not defined in Catalog or has no default value
                       XPath: /OpenSCENARIO/Catalog/Vehicle[3]/Performance

This is now fixed with a classification function that tells whether a string is an expression, a parameter or just a plain string

How was the PR tested?

1. Unit-test with sample data. All unit tests passed.

Notes

utils test function:

>>> utils.get_attribute_type("TEST")
<AttributeType.VALUE: 0>
>>> utils.get_attribute_type("$TEST")
<AttributeType.PARAMETER: 2>
>>> utils.get_attribute_type("${TEST")
<AttributeType.VALUE: 0>
>>> utils.get_attribute_type("${1/3}")
<AttributeType.EXPRESSION: 1>

[hoangtungdinh]

Thanks @romanodanilo