feat: add --single-active-backend to allow only one backend active at the time (#925)

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

api/options/options.go

@@ -33,6 +33,8 @@ type Option struct {
 	ExternalGRPCBackends map[string]string
 
 	AutoloadGalleries bool
+
+	SingleBackend bool
 }
 
 type AppOption func(*Option)
@@ -58,6 +60,10 @@ func WithCors(b bool) AppOption {
 	}
 }
 
+var EnableSingleBackend = func(o *Option) {
+	o.SingleBackend = true
+}
+
 var EnableGalleriesAutoload = func(o *Option) {
 	o.AutoloadGalleries = true
 }