Send "Expiry time window" data when registering against OpenBAS

[antoinemzs]

Use case

It is useful for OpenBAS to know within which time window a given collector will consider an expectation, before expiring it.

Current Workaround

No practical workaround. It's current practice to hardcode a 45-minute window in collectors but it's not reasonable to hardcode this in OpenBAS too.

Proposed Solution

Add the configured expiry time window to the data uploaded to OpenBAS when the collector registers against the server. It's the correct time and to do it as collectors register on startup and this is the time when configuration is loaded, hence this would allow for changing this value and this owuld be reflected on OpenBAS.