Enumerate available fonts through the native API on macOS

[0xced]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

macOS provides the CTFontManagerCopyAvailableFontURLs() method to get a list of all available fonts. Use it to iterate available fonts on macOS instead of scanning a list of hardcoded directories.

Use the Switch.SixLabors.Fonts.DoNotUseNativeSystemFontsEnumeration AppContext switch to opt-out of the native system fonts enumeration.

Running the ListFonts sample code before this change on my Mac would yield 628 fonts and 726 after this change because CTFontManagerCopyAvailableFontURLs knows about downloadable fonts.

[codecov]

Codecov Report

Merging #263 (7f953ed) into main (5359ec7) will decrease coverage by 0%.
The diff coverage is 27%.

@@         Coverage Diff         @@
##           main   #263   +/-   ##
===================================
- Coverage    83%    83%   -1%     
===================================
  Files       186    187    +1     
  Lines      9474   9517   +43     
  Branches   1493   1499    +6     
===================================
+ Hits       7936   7939    +3     
- Misses     1193   1231   +38     
- Partials    345    347    +2     

Flag	Coverage Δ
unittests	83% <27%> (-1%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...SixLabors.Fonts/Native/MacSystemFontsEnumerator.cs	0% <0%> (ø)
src/SixLabors.Fonts/SystemFontCollection.cs	57% <69%> (-3%)	⬇️

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[JimBobSquarePants]

Well this is cool! Thanks!

I'm not super well versed with dll Importing so I'm gonna see if I can get a second opinion for reviewing.

[JimBobSquarePants]

This all looks like it's working well to me an is very well documented to approving.

Thanks @0xced for your help! 👍

[0xced]

Awesome, thanks for merging. Once the cff-support support branch will be merged, a lot of fonts will be available on macOS! 😀

Also, I'll make sure not to use file scoped namespaces in my future pull requests.

[JimBobSquarePants]

No worries!

Working hard on CFF but it's a huge task. Could take me a while.

Also, I'll make sure not to use file scoped namespaces in my future pull requests.

Once I finally shift a V1 I'll be moving everything to the latest and greatest so we can use things like that without issue.