Add copyright notices to lightning-transaction-sync modules

[tnull]

Closes #3288.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.83%. Comparing base (b023eed) to head (c15968c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3290      +/-   ##
==========================================
- Coverage   89.84%   89.83%   -0.02%     
==========================================
  Files         126      126              
  Lines      103263   103263              
  Branches   103263   103263              
==========================================
- Hits        92778    92767      -11     
- Misses       7763     7770       +7     
- Partials     2722     2726       +4     

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