move MetaCPAN::Web::Test to t/lib

[haarg]

MetaCPAN::Web::Test is only used by the tests, so it should be in the test libraries. Also consistently load from t/lib in all tests.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.01%. Comparing base (2be9dab) to head (c0d144f).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3063      +/-   ##
==========================================
- Coverage   73.02%   72.01%   -1.01%     
==========================================
  Files          74       71       -3     
  Lines        2543     2423     -120     
  Branches      356      338      -18     
==========================================
- Hits         1857     1745     -112     
+ Misses        555      554       -1     
+ Partials      131      124       -7     

see 4 files with indirect coverage changes