refactor: unit testable units and cleaner dep injection

go/internal/particle/networkmembershipchecker.go

@@ -0,0 +1,10 @@
+package particle
+
+import "context"
+
+//go:generate mockgen -source ./networkmembershipchecker.go -destination ./mocks/networkmembershipchecker.go
+
+type NetworkMembershipChecker interface {
+	// IsMember returns true if the humanId is a member of the network.
+	IsMember(ctx context.Context, networkID, humanId string) (bool, error)
+}