Cleanup `PackageTemplate`a bit

[TheBlueMatt]

Digging into better aggregation turned up a bunch of nonsense in PackageTemplate that is gonna lead to us breaking things in the future, so since I actually understand how the hell it works I figured I should clean it up a bit so someone else can understand it.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 99.28571% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.99%. Comparing base (bc1931b) to head (58d0ca3). Report is 28 commits behind head on main.

Files with missing lines	Patch %	Lines
lightning/src/chain/onchaintx.rs	80.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3297      +/-   ##
==========================================
+ Coverage   89.62%   89.99%   +0.37%     
==========================================
  Files         127      127              
  Lines      103517   107521    +4004     
  Branches   103517   107521    +4004     
==========================================
+ Hits        92780    96768    +3988     
- Misses       8041     8145     +104     
+ Partials     2696     2608      -88     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[arik-so]

I'm sure you already noticed, but CI's failing :/

[TheBlueMatt]

I had not, thanks. Fixed.