Add assert for fetch_att and store_att_byval

[mkindahl]

These two functions throw an error if you pass in a strange combination of typbyval and typlen, so we assert on bad values to get a backtrace.

Disable-check: force-changelog-file

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

Project coverage is 82.55%. Comparing base (59f50f2) to head (0cff399).
Report is 561 commits behind head on main.

Files with missing lines	Patch %	Lines
src/utils.h	66.66%	0 Missing and 1 partial ⚠️
tsl/src/compression/algorithms/datum_serialize.c	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7365      +/-   ##
==========================================
+ Coverage   80.06%   82.55%   +2.49%     
==========================================
  Files         190      229      +39     
  Lines       37181    42731    +5550     
  Branches     9450    10734    +1284     
==========================================
+ Hits        29770    35278    +5508     
- Misses       2997     3168     +171     
+ Partials     4414     4285     -129     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.