Provide an option to raise an error on invalid escape sequences in regular expressions

[metthal]

The feature of YARA is that it allows invalid escape sequences and never raises an error on them. We behave the same way in yaramod. However, sometimes it is desirable to find out about these invalid escape sequences since you might want to use those regular expressions somewhere else and not all regex engines are so tolerant.

Definition of done:

Yaramod will have opt-in option to raise and error on invalid escape sequence when creating Yaramod instance.