Make sure multiple setup runs are ignored

If the `configure` initializers or `startManager` are invoked multiple times, this can cause undefined behaviour and crashes. Hence we simply ignore if they are invoked multiple times.
Add warnings to the console for the last commit

Notify the developer about the issues by logging a warning to the console when the SDK is initialized more than once or startManager is invoked multiple times
Some localization updates

Change some strings for the new attachment feature. Translations still pending.
Make keychain data better accessible

Use `kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly` instead of `kSecAttrAccessibleWhenUnlockedThisDeviceOnly` when storing data into the keychain to allow the data to be also fetched when the app is launched in the background