Improve the Yaml configuration loader

[caendesilva]

Overview:

• Refactors and improves the code
• New attempt at Configuration loader improvements  #1691
• Fixes Configuration loader should be able to set documentation sidebar title from Hyde YAML config #1523

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (ab9519f) to head (b14d20b).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##              master     #1770   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
- Complexity      1750      1758    +8     
===========================================
  Files            180       180           
  Lines           4674      4689   +15     
===========================================
+ Hits            4674      4689   +15     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[caendesilva]

Unless this is modified to another pattern, we should also support this

    'description' => env('SITE_NAME', 'HydePHP').' RSS Feed',

And of course this

    Meta::property('site_name', env('SITE_NAME', 'HydePHP')),

I think these are all the remaining ones

[caendesilva]

It's a bit hard to test, but I confirmed manually that setting the site name in the environment variables, that takes precedence over all this, as those are evaluated before this.

[caendesilva]

    Meta::property('site_name', env('SITE_NAME', 'HydePHP')),

Not sure how we can set this, since it's not keyed.

Edit: We can probably loop through the array, but this is starting to get complex. I think adding a dedicated environment configuration loader to get data from the Yaml file could work if it's in between the environment and configuration loaders