Re-export lightning_types in top-level lightning modules

[TheBlueMatt]

Since we now have many types in one place, it makes sense to export them in that place. Further, doing so finally somewhat starts to reduce our lightning::ln module size, which historically is the dumping ground for everything when most things really should be top-level modules in lightning.

Here we take a step in the right direction by exporting lightning_types as lightning::types and encouraging users to use those paths directly rather than the ones in lightning::ln.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.70%. Comparing base (ccce9d9) to head (1e1b8ec).
Report is 34 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3253      +/-   ##
==========================================
+ Coverage   89.68%   89.70%   +0.01%     
==========================================
  Files         124      124              
  Lines      102386   102386              
  Branches   102386   102386              
==========================================
+ Hits        91827    91844      +17     
+ Misses       7857     7839      -18     
- Partials     2702     2703       +1     

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