Add fmt::Debug implementation for FundedChannel

[joostjager]

To aid with debugging in tests.

[ldk-reviews-bot]

👋 Thanks for assigning @valentinewallace as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.84%. Comparing base (17f7858) to head (067d659).
⚠️ Report is 21 commits behind head on main.

Files with missing lines	Patch %	Lines
lightning/src/sign/type_resolver.rs	0.00%	3 Missing ⚠️
lightning/src/util/test_utils.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4183   +/-   ##
=======================================
  Coverage   88.83%   88.84%           
=======================================
  Files         180      180           
  Lines      137504   137510    +6     
  Branches   137504   137510    +6     
=======================================
+ Hits       122155   122165   +10     
+ Misses      12538    12535    -3     
+ Partials     2811     2810    -1     

Flag	Coverage Δ
fuzzing	20.90% <0.00%> (-0.59%)	⬇️
tests	88.68% <0.00%> (+<0.01%)	⬆️

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[jkczyz]

Why are some of these not conditional derived?

[joostjager]

I followed the path of non-conditional derivation for non-public types, and only adding conditionals for public types or when required transitively. @TheBlueMatt mentioned offline "For internal types we should probably mostly just upstream Debug on most structs…"

[jkczyz]

LGTM. CI has some failures but look unrelated.