MRG: update Makefile with 'offline', 'wheel'

[ctb]

Fixes #3571

Updates include/sourmash.h rule to be verbose;
Adds wheel and offline targets for build.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.32%. Comparing base (d72a759) to head (e67bd56).

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3579      +/-   ##
==========================================
+ Coverage   88.01%   92.32%   +4.30%     
==========================================
  Files         136      104      -32     
  Lines       22275    12949    -9326     
  Branches     2225     2225              
==========================================
- Hits        19606    11955    -7651     
+ Misses       2356      681    -1675     
  Partials      313      313              

Flag	Coverage Δ
hypothesis-py	?
python	92.32% <ø> (ø)
rust	?

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[ctb]

@luizirber it looks like the build error has nothing to do with the PR 😭 . Thoughts?