Update make_string util to clean up bad values

[EtiennePelletier]

From exif-samples-master, the type of the seq arguments for a few entries (mostly UserComment) in util.make_string is a list. mypy still succeeds after the type annotation amendment. There is also no value in keeping a list of null bytes.

On another note, many other UserComment only contain spaces and some other fields contained trailing spaces (seen null character as well).

Finally, Nikon MakerNote ISOSetting is int16u[2] and should not be stringified. https://exiftool.org/TagNames/Nikon.html Sample values seen include [0, 0] and [0, 200], which were respectively being converted to '[0, 0]' and '}' by make_string.

The test diff output does not clearly show the effect of .strip(), so here it is along one example of the printable value of the IfdTag:

-  "EXIF UserComment": "                                                                                                                     ",
+  "EXIF UserComment": "",

$ diff -y --suppress-common-lines exif-samples-master/dump exif-samples-master/dump_test
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
MakerNote MakernoteVersion (Undefined): [0, 2, 0, 0]          | MakerNote MakernoteVersion (Undefined): 0200
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined): [0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  | EXIF UserComment (Undefined): 
EXIF UserComment (Undefined):                                 | EXIF UserComment (Undefined): 

@ianare, if you approve this PR, I can modify the exif-sample-master/dump afterwards to reflect changes :)

🐍 🤹‍♂️

[ianare]

Great, thanks! If you can do the PR for the samples, that would be perfect. I'll approve this but wait for the samples to be done before merging to avoid false failures.

[EtiennePelletier]

Here we go: ianare/exif-samples#5