Offer Media management testing as part of TestBasicOrchardFeaturesAsync() too (OSOE-423)

[Piedone]

To include more tests of basic Media file management (in addition to the setup recipe potentially referencing files), let's add a test for Media operations too.

• Test the basics of Media Library: Upload file in root (check if the file is now properly accessible), create folder, upload file to folder, delete file, delete folder. Do this with JPGs and PDFs.
• Add a new method for this to BasicOrchardFeaturesTestingUITestContextExtensions, like TestMediaOperations().
• Execute this as part of TestBasicOrchardFeaturesExceptSetupAsync() too.
• This needn't use Atata page classes like the other similar tests.

Jira issue