[FEAT] Implement service provider checks in module initialisation #106

Modules like Email, SMS and Storage depend either optionally or entirely on third party service providers.
Accessing and making use of said providers might not always be possible due to configured credentials being invalid, their service going down or even the backend user's account running low on credit.

Instead of just assuming a third-party dependent module is online as long as its configuration specifies active: true and it hasn't yet crashed, we should ideally be performing some checks to verify our connection is not only available, but also functional (that is to say, not connected, but unable to send emails due to a low credit block for instance).

These checks would also prove useful in notifying modules making use of a service-dependent module as to the latter's actual state.
For instance, Authentication's local authentication strategy makes optional use of Email for registration verification etc.
It's no good knowing that Email is online and "active" when in reality it could possibly be incapable of sending any emails.
This could also let us temporarily disable certain routes (route re-registration) on an inactive Email onConfig event and whatnot.