Improve publication feature testing

[caendesilva]

• Adds additional tests for the compiling of publication pages
• Updates seeder to seed Markdown body content Add a package that provides a publications feature #685 (comment)

[codecov]

Codecov Report

Merging #815 (5bc340f) into publications-feature (aead5e2) will increase coverage by 0.47%.
The diff coverage is n/a.

❗ Current head 5bc340f differs from pull request most recent head f8dc263. Consider uploading reports for the commit f8dc263 to get more accurate results

@@                    Coverage Diff                     @@
##             publications-feature     #815      +/-   ##
==========================================================
+ Coverage                   99.46%   99.94%   +0.47%     
+ Complexity                   3016     1510    -1506     
==========================================================
  Files                         338      169     -169     
  Lines                        7538     3774    -3764     
==========================================================
- Hits                         7498     3772    -3726     
+ Misses                         40        2      -38     

Impacted Files	Coverage Δ
...rk/src/Framework/Actions/SeedsPublicationFiles.php	100.00% <0.00%> (ø)
...rk/src/Framework/Actions/SeedsPublicationFiles.php
...rk/src/Console/Commands/SeedPublicationCommand.php
...framework/src/Console/Commands/MakePostCommand.php
...work/src/Framework/Concerns/ValidatesExistence.php
...ckages/framework/src/Support/Models/DateString.php
.../Framework/Features/Metadata/GlobalMetadataBag.php
.../framework/src/Support/Models/ValidationResult.php
.../framework/src/Framework/Services/AssetService.php
packages/framework/src/Facades/Includes.php
... and 162 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.