Use "chrome.storage.sync" instead of "chrome.storage.local" for user settings, allowing to sync between browsers (Chrome)

This should be discussed, since it’s a nice-to-have feature to be able to have the same settings on all Chrome browsers which are already being synced.

This can easily be achieved by using “chrome.storage.sync” instead of “chrome.storage.local” in UtilsService and some other places.

However, I don’t know if it’s OK, security-wise, to sync all the stored variables, and there should be either a blacklist of variables which should not be synced or a whitelist of variables which can be synced.

Possible problematic variables to sync: accessToken, encPrivateKey, encKey, encOrgKeys, key, …