add sorting to output of parse_xml_report.py

    PASS = "PASS"

SORT_KEYS = ["MAX_ABS_DIFF", "MLD", "MIN_SSNR", "MIN_ODG"]

SORT_ASCENDING = [False, False, True, True]

class TestcaseParser(dict):

    def __init__(self, testcases: list):

        super().__init__()

    def to_df(self) -> pd.DataFrame:

        testcases = list(self.values())

        df = pd.DataFrame(testcases)

        for key in SORT_KEYS:

            df[key] = pd.to_numeric(df[key], errors="coerce")

        df = df.sort_values(by=SORT_KEYS, ascending=SORT_ASCENDING)

        return df