Refine Makefile for installation

Previously, this Makefile could only update existing installations of
Docker extension installations. With this change, it will either install
or update depending on whether it's already installed.

I'm not sure if it was always broken of if it was something Docker
just changed, but either way — it's fixed now.

Makefile

@@ -18,7 +18,9 @@ extension: ## Build service image to be deployed as a desktop extension
 .PHONY: extension
 
 install-extension: extension ## Install extension image Docker desktop
-	docker extension update $(LOCAL_IMAGE_NAME)
+	@if $$(docker extension ls | grep -q $(LOCAL_IMAGE_NAME)); \
+		then docker extension update $(LOCAL_IMAGE_NAME); \
+		else docker extension install $(LOCAL_IMAGE_NAME); fi
 .PHONY: install-extension
 
 dev-extension: install-extension
@@ -27,7 +29,7 @@ dev-extension: install-extension
 .PHONY: dev-extension
 
 remove-extension:
-	@docker extension remove $(LOCAL_IMAGE_NAME)
+	@docker extension rm $(LOCAL_IMAGE_NAME)
 .PHONY: remove-extension
 
 push-extension: ## Build & Upload extension image to hub. Do not push if tag already exists: make push-extension tag=0.1