[MAINT] Utils library Qt-less refactor (Part 1 of many)

[gabrielbmotta]

This goes over a majority of the utils library and adds a std lib api (and a std lib backend) to most classes and static functions.

• Overloaded functions with Qt-type parameters and return values with std lib versions.
• Changes internal logic where applicable to use std lib containers/classes
• When faced with functions with no input parameters and a qt return type, overloaded added and commented out.

Also:

• min c++ version set to c++ 17 for use of filesystem library. Is this ok? this is a 5 year old standard at this point.
  (reverted, was causing issues with ubuntu 18 and osx 10.15 and lower std lib version. No longer using filesystem lib. )

• Because adding more code results in a lower code coverage percentage even though the functions I overloaded were not being tested anyway (I think), I also wrote a test for circular buffer to bump up code coverage.

What is missing:

• Going over threading use of QtConcurrent::mapReduced in spectrogram.h/cpp. Somewhat relates to the now-dormant time frequency PR WIP [ENH] Time Frequency Plugins for MNE Scan and MNE Analyze #785
• QSemaphore use in circular buffer. Std lib of semaphore is c++20, and that is perhaps too recent a cut off point. We could implement our own semaphore with the same api as the c++20 version to make later replacement easy.

[juangpc]

great!

[codecov]

Codecov Report

Merging #881 (937633a) into main (bd31738) will increase coverage by 6.08%.
The diff coverage is 0.74%.

@@            Coverage Diff             @@
##             main     #881      +/-   ##
==========================================
+ Coverage   30.20%   36.28%   +6.08%     
==========================================
  Files         452      195     -257     
  Lines       39208    11805   -27403     
==========================================
- Hits        11841     4284    -7557     
+ Misses      27367     7521   -19846     

Impacted Files	Coverage Δ
libraries/utils/file.cpp	0.00% <ø> (ø)
libraries/utils/ioutils.cpp	23.68% <0.00%> (-6.32%)	⬇️
libraries/utils/kmeans.cpp	0.27% <ø> (ø)
libraries/utils/kmeans.h	0.00% <ø> (ø)
libraries/utils/layoutloader.cpp	0.00% <0.00%> (ø)
libraries/utils/layoutmaker.cpp	0.79% <0.00%> (-0.68%)	⬇️
libraries/utils/mnemath.cpp	20.54% <0.00%> (-7.49%)	⬇️
libraries/utils/mnemath.h	0.00% <ø> (-16.00%)	⬇️
libraries/utils/spectral.cpp	13.25% <0.00%> (-1.82%)	⬇️
libraries/utils/spectral.h	0.00% <ø> (ø)
... and 286 more

[gabrielbmotta]

The qt installer action for linux is failing now working broken again.