Refactor check-platform-reqs to use InstalledRepository and look for providers as well as platform packages, fixes #8645, closes #8676
Refactor check-platform-reqs to use InstalledRepository and look for providers as well as platform packages, fixes #8645, closes #8676

Co-authored-by: Ellis <656c4c8af1cac6fe07865bfd1e7c8ca9439cde8d@nuglif.com>
Co-authored-by: Jordi Boggiano <0712a68aba493ca0413b8a0d0238658b52132f56@seld.be>

johnstevenson/composer,staabm/composer,milleruk/composer,fabpot/composer,stefangr/composer,nicolas-grekas/composer,stof/composer,composer/composer,naderman/composer,alcohol/composer,pierredup/composer,floverdevel/composer,localheinz/composer