core: remove obsolete signaling engine

[multun]

This code:

• is not used anywhere: it was previously used to compute signal updates for standalone simulation. STDCM uses something else
• does not do the right thing: it conflates routes and blocks
• is an obstacle to current efforts: the tests for this module fail if we fix routes in the example infrastructure

[codecov]

Codecov Report

Merging #4744 (3f4d4f8) into dev (f43b725) will decrease coverage by 0.21%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                dev    #4744      +/-   ##
============================================
- Coverage     20.30%   20.09%   -0.21%     
+ Complexity     2329     2234      -95     
============================================
  Files           876      870       -6     
  Lines         89096    88936     -160     
  Branches       2319     2292      -27     
============================================
- Hits          18091    17872     -219     
- Misses        69722    69790      +68     
+ Partials       1283     1274       -9     

Flag	Coverage Δ
core	78.95% <ø> (-0.92%)	⬇️

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

see 7 files with indirect coverage changes