fix: include URL to I-D Archive in WGLC messages

[rjsparks]

This is a simple fix to pass a URL into a template rendering context.

It is a complicated fix to the test framework (that can affect production code, but currently doesn't), by clearing an internal cache around state information when using refresh_from_db.

The PR enhances the tests of the issue_wg_lc view. It was created with the assistance of Claude.

Fixes #11041

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.52%. Comparing base (4641d0d) to head (46f4e02).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11056      +/-   ##
==========================================
+ Coverage   88.51%   88.52%   +0.01%     
==========================================
  Files         334      334              
  Lines       45102    45107       +5     
==========================================
+ Hits        39924    39933       +9     
+ Misses       5178     5174       -4     

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