Implement RFC 73: Stricter connections.

[zyp]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.28%. Comparing base (f6d02d2) to head (88f0401).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
amaranth/lib/wiring.py	75.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1637      +/-   ##
==========================================
- Coverage   91.29%   91.28%   -0.02%     
==========================================
  Files          44       44              
  Lines       11493    11517      +24     
  Branches     2238     2242       +4     
==========================================
+ Hits        10493    10513      +20     
- Misses        837      842       +5     
+ Partials      163      162       -1     

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[whitequark]

Needs at the very least:

• Tests for changes in lib.data and lib.enum
• Changelog update

[whitequark]

LGTM, thank you!