olevba: Add zipfile content read limit

[dlucredativ]

Even small input files can lead to memory exhaustion inside oletools.olevba.VBA_Parser.open_openxml, as zipped contents are read into memory (https://github.com/decalage2/oletools/blob/master/oletools/olevba.py#L2876-L2879).

As a safety-measure one could implement a configurable limit for those reads.