MAINT: Generalize the method of obtaining space_code

[ssjkamei]

I made changes to separate the part that gets the space code from the part that analyzes it for clarity. I hope you like it.

I was wondering about the space_code determination for type1_alternative.
Perhaps the comparison of the if statement itself is not being used, as I think the content is inadequate.

            if words[2].decode() == b" ":
                space_code = i

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.43%. Comparing base (fcb103a) to head (83d4899).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2891      +/-   ##
==========================================
+ Coverage   96.36%   96.43%   +0.07%     
==========================================
  Files          52       52              
  Lines        8739     8724      -15     
  Branches     1727     1721       -6     
==========================================
- Hits         8421     8413       -8     
+ Misses        186      182       -4     
+ Partials      132      129       -3     

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[ssjkamei]

At the point where space_code is returned, there is logic that is incorrectly returning Width, and when this part of the code is erased, it no longer enters the code below.
I was not sure if I should delete it, but I did because it would cause an error in code coverage.
I don't think I will put back no encoding on the code.

The part that was wrong: return encoding, _default_fonts_space_width[cast(str, ft["/BaseFont"])]

def parse_encoding(
    ft: DictionaryObject, space_code: int
) -> Tuple[Union[str, Dict[int, str]], int]:
    encoding: Union[str, List[str], Dict[int, str]] = []
    if "/Encoding" not in ft:
        try:
            if "/BaseFont" in ft and cast(str, ft["/BaseFont"]) in charset_encoding:
                encoding = dict(
                    zip(range(256), charset_encoding[cast(str, ft["/BaseFont"])])
                )
            else:
                encoding = "charmap"
            return encoding, _default_fonts_space_width[cast(str, ft["/BaseFont"])]
        except Exception:
            if cast(str, ft["/Subtype"]) == "/Type1":
                return "charmap", space_code
            else:
                return "", space_code
.....

Codes that were erased:

    # encoding can be either a string for decode
    # (on 1,2 or a variable number of bytes) of a char table (for 1 byte only for me)
    # if empty string, it means it is than encoding field is not present and
    # we have to select the good encoding from cmap input data
    if encoding == "":
        if -1 not in map_dict or map_dict[-1] == 1:
            # I have not been able to find any rule for no /Encoding nor /ToUnicode
            # One example shows /Symbol,bold I consider 8 bits encoding default
            encoding = "charmap"
        else:
            encoding = "utf-16-be"

[ssjkamei]

Please review the code check as it has passed.

[stefan6419846]

Suggested change

	# apply rule from PDF ref 1.7 §5.9.1, 1st bullet :
	# Apply rule from PDF ref 1.7 §5.9.1, 1st bullet:

[stefan6419846]

Suggested change

	# if encoding is an str it is expected to be a identity translation
	# If encoding is a string it is expected to be an identity translation.