Allow Notifications for Non Multi-Tenant Scenarios

[tsutomi]

The notification service of the Deveel.Webhooks project is currently supporting only multi-tenant scenarios for the notifications, which requires additional configurations of the applications, to circumvent the limitation (eg. adding the multi-tenant support and use only one static tenant).

Although this is a feature that has sense in large-scale scenarios, in most of the situations this might be excessive and hard to handle.

The proposed solution might provide one or more of the two options:

• Multi-Tenant Notifier - A notifier service that is requiring the identifier of the tenant to resolve webhook subscriptions, provided as alternative to another service that will not require this input and use the regular storage
• Implicit Resolution of the Tenants - The notifier service will not require the unique identifier of the tenant to notify, scanning for all tenants registered in the current context, notifying to all subscriptions matching the event
• Tenant Identifier in Event - The EventInfo structure might be extended with an optional the identifier of the tenant of the subscriptions to the event, to let the notifier identify and resolve subscriptions specific for that context