Add event sink API and CLI commands (#9226)

Co-authored-by: Drew Bailey <2614075+drewbailey@users.noreply.github.com>

vendor/github.com/hashicorp/nomad/api/event_sink.go

@@ -0,0 +1,57 @@
+package api
+
+import "sort"
+
+type SinkType string
+
+const (
+	SinkWebhook SinkType = "webhook"
+)
+
+type EventSink struct {
+	ID   string
+	Type SinkType
+
+	Topics map[Topic][]string
+
+	Address string
+
+	// LatestIndex is the latest reported index that was successfully sent.
+	// MangedSinks periodically check in to update the LatestIndex so that a
+	// minimal amount of events are resent when reestablishing an event sink
+	LatestIndex uint64
+
+	CreateIndex uint64
+	ModifyIndex uint64
+}
+
+type EventSinks struct {
+	client *Client
+}
+
+func (c *Client) EventSinks() *EventSinks {
+	return &EventSinks{client: c}
+}
+
+func (e *EventSinks) List(q *QueryOptions) ([]*EventSink, *QueryMeta, error) {
+	var resp []*EventSink
+	qm, err := e.client.query("/v1/event/sinks", &resp, q)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	sort.Slice(resp, func(i, j int) bool { return resp[i].ID < resp[j].ID })
+	return resp, qm, nil
+}
+
+func (e *EventSinks) Register(eventSink *EventSink, w *WriteOptions) (*WriteMeta, error) {
+	wm, err := e.client.write("/v1/event/sink/"+eventSink.ID, eventSink, nil, w)
+	if err != nil {
+		return nil, err
+	}
+	return wm, nil
+}
+
+func (e *EventSinks) Deregister(name string, w *WriteOptions) (*WriteMeta, error) {
+	return e.client.delete("/v1/event/sink/"+name, nil, w)
+}