Create Sentry exception when we fail to fetch

[six7]

In order to better understand when certain services such as Heroku show outages we should trigger dedicated Sentry exceptions for each of the following services

• When LaunchDarkly fails to fetch
• When our license key validation fails to fetch (due to a server outage)

Each of these should have their own handled exception, we need to be aware of that so we can make decisions if our choice of provider is still the right one.