Add Manager and Provider structures with streaming capabilities

services/marketdata/internal/provider/provider.go

@@ -0,0 +1,19 @@
+package provider
+
+import (
+	"gitlab.michelsen.id/phillmichelsen/tessera/services/marketdata/internal/router"
+)
+
+type Provider interface {
+	Start() error
+	Stop() error
+
+	RequestStream(subject string, channel chan router.Message) error
+	CancelStream(subject string)
+	GetActiveStreams() []string
+	IsStreamActive(subject string) bool
+
+	Fetch(subject string) (router.Message, error)
+
+	IsValidSubject(subject string, isFetch bool) bool
+}