Allows to inject something into the default content policy. This is for
example useful when you're injecting Javascript code into a view belonging
to another controller and cannot modify its Content-Security-Policy itself.
Note that the adjustment is only applied to applications that use AppFramework
controllers.
To use this from your `app.php` use `\OC::$server->getContentSecurityPolicyManager()->addDefaultPolicy($policy)`,
$policy has to be of type `\OCP\AppFramework\Http\ContentSecurityPolicy`.
To test this add something like the following into an `app.php` of any enabled app:
```
$manager = \OC::$server->getContentSecurityPolicyManager();
$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFrameDomain('asdf');
$policy->addAllowedScriptDomain('yolo.com');
$policy->allowInlineScript(false);
$manager->addDefaultPolicy($policy);
$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFontDomain('yolo.com');
$manager->addDefaultPolicy($policy);
$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFrameDomain('banana.com');
$manager->addDefaultPolicy($policy);
```
If you now open the files app the policy should be:
```
Content-Security-Policy:default-src 'none';script-src yolo.com 'self' 'unsafe-eval';style-src 'self' 'unsafe-inline';img-src 'self' data: blob:;font-src yolo.com 'self';connect-src 'self';media-src 'self';frame-src asdf banana.com 'self'
```
This adds a new CSRF manager for unit testing purposes, it's interface is based upon https://github.com/symfony/security-csrf. Due to some of our required custom changes it is however not possible to use the Symfony component directly.
CredentialsManager performs a simple role, of storing and retrieving
encrypted credentials from the database. Credentials are stored by user
ID (which may be null) and credentials identifier. Credentials
themselves may be of any type that can be JSON encoded.
The rationale behind this is to avoid further (mis)use of
oc_preferences, which was being used for all manner of data not related
to user preferences.
Otherwise an empty string is used indicating the cookie is only valid for those resources. This can lead to eunexpected behaviour.
Fixes https://github.com/owncloud/core/issues/19196
The ETag set in the IF_NONE_MODIFIED header is wraped in quotes (").
However the ETag that is set in response is not (yet). Also we need to
cast the ETag to a string.
* Added unit test
