Deprecate some routes by comments

[christianlupus]

We have still some old API endpoints that should be cleaned up. This PR should clean up no longer used routes and structure the code better.

[codecov]

Codecov Report

Merging #580 (c139e57) into master (eeb9e1a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##             master    #580   +/-   ##
========================================
  Coverage      1.01%   1.01%           
  Complexity      444     444           
========================================
  Files            14      14           
  Lines          1385    1385           
========================================
  Hits             14      14           
  Misses         1371    1371           

Flag	Coverage Δ	Complexity Δ
integration	0.00% <ø> (ø)	0.00 <ø> (ø)
unittests	1.01% <ø> (ø)	0.00 <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ	Complexity Δ
lib/Controller/MainController.php	0.00% <ø> (ø)	40.00 <0.00> (ø)

[christianlupus]

@Teifun2 please look if you are using one of the Unknown usage endpoints. These might still work currently but if we are deciding to deprecate them (I assume so), this might cause issues for you. There are alternatives under the /api/recipes tree.