added trigger controller and reconciler

[astelmashenko]

A custom broker implementation consists of few components:

1. Feature/natsjs broker step1 #715 broker controller, to be able to specify NatsJetstreamBroker class for a broker CRD
2. added trigger controller and reconciler #716 trigger controller, to receive events for eventing triggers which are subscribed to the NatsJetstreamBroker class and reconcile subscriptions to JetStream
3. ingress, which accepts http requests to broker and stores it into JetStream stream storage
4. filter, which creates consumers to JetStream, get messages, filter them out and sends to targets according to triggers configuration
5. configuration is a set of yaml files describe CRD, service accounts, roles and permissions of above components
6. e2e tests/docs/examples

Custom broker implemnetation step2: trigger controller

Brokers work with eventing triggers, since there custom broker class for NatsJetsream we need to reac when triggers are created/updated/deleted for brokers with the new custom broker class. An example of broker trigger.

Broker:

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: example-broker
  annotations:
    eventing.knative.dev/broker.class: NatsJetStreamBroker

Trigger:

apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: exact-filter-trigger
  namespace: default
spec:
  broker: example-broker
  filters:
    - exact:
        type: com.example.order.created
  subscriber:
    ref:
      apiVersion: v1
      kind: Service
      name: order-processor

There are two main files: pkg/broker/trigger/controller.go and pkg/broker/trigger/reconciler.go
Trigger controller loads nats conn options, subscribes to events from trigger and broker CRD filtering by broker class to react on CRD changes; and create a reconciler.

Trigger reconciler cheks trigger related things: broker status, subscriber, dlq, etc and updates trigger conditions and overall status. JetStream specific is it checks if a stream exists, and creates/updates a consumer for the Nats stream. Consumer configuration is based on Trigger spec.Delivery, to utilize retries based on JetStream consumer features, instead of in-memory retries, it will be visible in future PR related to filter.

[knative-prow]

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[codecov]

Codecov Report

❌ Patch coverage is 42.30769% with 120 lines in your changes missing coverage. Please review.
✅ Project coverage is 31.53%. Comparing base (1f2f843) to head (4864918).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/broker/trigger/reconciler.go	54.01%	61 Missing and 2 partials ⚠️
pkg/broker/trigger/controller.go	20.00%	56 Missing ⚠️
cmd/broker/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #716      +/-   ##
==========================================
+ Coverage   30.81%   31.53%   +0.72%     
==========================================
  Files          53       55       +2     
  Lines        3096     3304     +208     
==========================================
+ Hits          954     1042      +88     
- Misses       2074     2192     +118     
- Partials       68       70       +2     

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[astelmashenko]

/assign @Cali0707