Resolution (macOS): improve detection

[CarterLi]

1. fix detection when screenresolution is not available
2. make scale factor detection actually work
3. remove screenresolution dependency

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Before

• neofetch reports the native / maximum resolution for the built-in display, instead of current scaled output resolution
• neofetch reports the output resolution for the external display, instead of scaled resolution
• neofetch fails to detect refresh rate for both displays
• neofetch fails to detect the scale factor, though it tries to detect it in the code

After

[CarterLi]

Ad: besides other fixes and improvements, detect these sh*t 10 times faster using fastfetch

[hykilpikonna]

Work on non-hidpi displays as well!

[hykilpikonna]

Thank you for your contribution!

This PR is merged into hyfetch since this repo (dylanaraps/neofetch) seems no longer maintained.

HyFetch is a fork of neofetch with LGBTQ pride flags, but the repo also maintains an updated version of the original neofetch, addressing many pull requests that are not merged in the original repo.

Read the "Running Updated Original Neofetch" section for more info!

[hykilpikonna]

Also just fixed some shellcheck warnings for you in hykilpikonna/hyfetch@526c97f

[CarterLi]

Applied changes suggested by @hykilpikonna and fixed a bug that neofetch fails to print scale factors when system_profiler fails to detect refresh rates.