Add Support for SNAPSHOT mode

Use the existing streaming cyclic buffer data to send snapshots

• Snapshot times refer to ref trigger event. E.g. if you specify 20us, than a single sample 20us after the ref trigger will be used for snapshot notify.
• Only relevant for the CONTINUES_* modes
• As soon as we have samples for all the specified snapshot times (up to 3), the client is notified (one client update per sample)
• It should be possible to specify up to 3 snapshot times per streaming channel/circularbuffer. Once these are specified and the buffer supports ClientNotificationType::SNAPSHOT, client updates for snapshot modes will be done.
• When new streaming data is incoming, we now need to check, if as well a snapshot client-update will be required.