Rename `*Url*` symbols to `*Path*`.

[mgautierfr]

Dirents' "url" are not really url. They are u8 arrays which serve as the main "key". Specification says that this u8 array store a utf-8 encoded string and we use this key as a path.

Public API already use path semantic so rename all internal symbols from url to path.

Fix #868

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 46.15385% with 28 lines in your changes are missing coverage. Please review.

Project coverage is 58.01%. Comparing base (96afb38) to head (54a3e6c).

Files	Patch %	Lines
src/fileimpl.cpp	27.27%	2 Missing and 14 partials :warning:
src/dirent.cpp	37.50%	0 Missing and 5 partials :warning:
src/fileheader.cpp	0.00%	1 Missing and 3 partials :warning:
src/archive.cpp	0.00%	0 Missing and 1 partial :warning:
src/dirent_accessor.cpp	75.00%	0 Missing and 1 partial :warning:
src/writer/creator.cpp	50.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #869 +/- ## ======================================= Coverage 58.00% 58.01% ======================================= Files 101 101 Lines 4622 4623 +1 Branches 1925 1925 ======================================= + Hits 2681 2682 +1 Misses 667 667 Partials 1274 1274 ```

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[mgautierfr]

Didn't you also have to replace all cURLy braces with PArenTHeses? :)

I've tried. But gcc didn't want. Hope next version of cpp will allow this.