Add apple app association

[hasanagh]

In order to support opening links on mobile. We should add apple app association to compose.

By adding under https://compose.graasp.com/.well-known/apple-app-site-association the following:

{
  "applinks": {
    "apps": [], // This is usually left empty, but still must be included
    "details": [
        {
            "appID": "org.graasp.mobile",
            "paths": ["/items/*"]
        },
        {
             "appIDs": [ "org.graasp.mobile"],
             "components": [
               {
                  "/": "/items/*",
                  "comment": "Matches any URL whose path starts with /items/"
               }
             ]
        }
    ]
  }
}