refactor(yaml): cleanup Schema

[timreichen]

Changes
This PR makes Schema an interface instead of a class.
As it turns out, compileList() just combines the implicit types with implicit types of the include schema, same with explicit types.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.27%. Comparing base (75cb767) to head (e8c14d9).
Report is 10 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #5715    +/-   ##
========================================
  Coverage   96.26%   96.27%            
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  Files         477      473     -4     
  Lines       38512    38366   -146     
  Branches     5589     5574    -15     
========================================
- Hits        37072    36935   -137     
+ Misses       1398     1389     -9     
  Partials       42       42            

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