Cleanup _oc_webroot stubs where possible

[max-nextcloud]

• test(jest): remove internal _oc_webroot stub
• test(cy): introduce cy.prepareWindowForSessionApi
• test(cy): refactor to use aliases
• test(cy): introduce cy.sessionUsers() for users endpoint
• test(api): split test and use .its and .should

[juliusknorr]

Looks good

just one failure remaining

FAIL src/tests/services/AttachmentResolver.spec.js
  Image resolver
    ✓ is a class with one constructor argument (29 ms)
    ✓ handles .attachments urls to own fileId via Text API (2 ms)
    ✓ leaves urls unchanged if they can be loaded directly (1 ms)
    ✓ handles .attachments urls to different fileId via webdav with text API fallback
    ✕ handles non-native urls wia webdav (3 ms)

  ● Image resolver › handles non-native urls wia webdav

    expect(received).toBe(expected) // Object.is equality

    Expected: "http://localhost/remote.php/dav/files/user-uid/parentDir/path/to/some%20image.png"
    Received: "http://localhost//remote.php/dav/files/user-uid/parentDir/path/to/some%20image.png"

      88 | 		const attachment = await resolver.resolve(src)
      89 | 		expect(attachment.isImage).toBe(true)
    > 90 | 		expect(attachment.previewUrl).toBe('http://localhost/remote.php/dav/files/user-uid/parentDir/path/to/some%20image.png')
         | 		                              ^
      91 | 	})
      92 |
      93 | })

      at Object.toBe (src/tests/services/AttachmentResolver.spec.js:90:33)

[mejo-]

/backport to stable29

[mejo-]

/backport to stable28