Improve e2e coverage for rclone-crypt vaults

[JammingBen]

• Image in a vault. Upload an image (testavatar.png) into a vault, open it in the preview app, assert it renders.

• Vault in a project space. Create a project space, create a vault in it with content, add a second user as member, have that user unlock the vault and open the file.

• Vault with no content and no integrity token. Create a regular folder folder.vault, open it, assert the unlock page is in setup mode. Set a passphrase, lock the vault, unlock again with that passphrase, assert entry works.

• Vault with content but no integrity token. A vault whose encrypted file was not created via Web must still unlock with the correct passphrase. You can simulate such a scenario by creating a regular folder, uploading an encrypted file into the folder and then renaming the folder to folder.vault. Accessing the folder should now prompt the user for a passphrase. Assert that unlocking works.

  Creating the unencrypted file for the test case: create a vault, use passphrase "test", remove the .vault suffix from the vault name, enter the folder, download the file. There is your encrypted file.