Remove STI, MTI, Composite, and Typed implementations

[alganet]

These features reached blocker limitations for future designs and will be re-planned from scratch later.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.17%. Comparing base (8fe033d) to head (1351bfb).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #116      +/-   ##
============================================
+ Coverage     99.06%   99.17%   +0.10%     
+ Complexity      170      149      -21     
============================================
  Files             3        3              
  Lines           429      362      -67     
============================================
- Hits            425      359      -66     
+ Misses            4        3       -1     

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