Gdi 95 add typing and comments in the fdp gdi repo

[a-nayden]

• type hints added
• logging for other that 200 FDP response
• fix parse None issue and tests accordingly
• use rdflib namespaces instead of hard-coded predicates

[brunopacheco1]

@a-nayden excelent PR, thanks a lot for all those changes.

[kburger]

Looks like a great improvement. There are some minor things to be gained, like fstrings vs .format and shorthand requests calls, but that's for later.