feat: ability to use custom storage for cookies

[gaspachoandalus]

Motivation
Cookies are stored in the webview localStorage.
According to #194, this may be an issue for some users who might want to store cookies in native storage, possibly secured.

This PR aims to add a new interface to cordova.plugin.http to be able provide a custom (and synchronous) storage implementation:

/**
 * Provides a custom cookie storage, to override the default localStorage
 * @param {Object} storageImpl 
 * @param {(name: string, value: string) => void} storageImpl.setItem 
 * @param {(name: string) => string} storageImpl.getItem 
 * @param {(name: string) => void} storageImpl.removeItem 
 */
function setCookieStorageImpl(storageImpl)

Some trivial usage could be:

cordova.plugin.http.setCookieStorageImpl({
  setItem: (name, value) =>
  {
    console.log(`setItem cookie ${name}`);
    localStorage.setItem(`myprefix_${name}`, value);
  },
  getItem: (name) =>
  {
    console.log(`getItem cookie ${name}`);
    return localStorage.getItem(`myprefix_${name}`);
  },
  removeItem: (name) =>
  {
    console.log(`removeItem cookie ${name}`);
    localStorage.removeItem(`myprefix_${name}`);
  }
})

[gaspachoandalus]

So, do you have any thoughts about this @silkimen ?

I can think of some features you might expect additionnally like:

• asynchronous behavior, so a Promise should be returned (but some synchronous API like setCookie or getCookieString would need to be asynchronous too ; also it may require implementing internally an asynchronous ToughCookie store)
• moving the cookie from the previous store to the new one when setCookieStorageImplis called ?

[silkimen]

Hi @gaspachoandalus, sorry for responding very late on this. 😓 Well, I like the idea of having a configurable storage, but Lindsor and also you got it correctly. All persistent storages I can think of (other than the LocalStorage) have an asynchronous API. So this feature won't help that much. I think we'll first need to check on how to allow asynchronous storages and how this affects the internals of this plugin.