Support blocking local storage "cookies"

[AlexTMjugador]

The Web Storage API supported by modern web browsers describes an alternative interface that JavaScript code can use to store persistent data on users' devices. This API has replaced cookies in several use cases, especially for rich web applications where the server does little processing. However, cookieconsent does not support blocking Web Storage API calls.

According to common interpretations of the Directive 2002/58/EC of the European Parliament and of the Council of 12 July 2002 concerning the processing of personal data and the protection of privacy in the electronic communications sector (Directive on privacy and electronic communications) (usually called "cookie law"), EU regulations are not limited to cookies. Paragraph 24 of that directive reads (emphasis mine):

Terminal equipment of users of electronic communications networks and any information stored on such equipment are part of the private sphere of the users requiring protection under the European Convention for the Protection of Human Rights and Fundamental Freedoms. So-called spyware, web bugs, hidden identifiers and other similar devices can enter the user's terminal without their knowledge in order to gain access to information, to store hidden information or to trace the activities of the user and may seriously intrude upon the privacy of these users. The use of such devices should be allowed only for legitimate purposes, with the knowledge of the users concerned.

Cookies are later mentioned in the directive as an example of information storage devices, but as the Web Storage API can also be used to implement information storage devices, the directive applies to it.

Given the fact that modern web applications are using the Web Storage API, that this repository aims to make it easy to comply with "EU regulation" and that the word "cookie" has been commonly overloaded to vaguely mean "information storage device" in this context, I think it'd be great for this project to support blocking Web Storage API usage 😄