Include “grocy” in names of podman objects

Since podman doesn't have namespacing for containers or volumes, we
should prefix container and volume names, so their relation to grocy
is clear.

Makefile

@@ -5,10 +5,10 @@ COMPOSER_VERSION = 2.1.5
 COMPOSER_CHECKSUM = be95557cc36eeb82da0f4340a469bad56b57f742d2891892dcb2f8b0179790ec
 IMAGE_TAG ?= $(shell git describe --tags --match 'v*' --dirty)
 IMAGE_PREFIX ?= docker.io/grocy
-BACKEND_CONTAINER_NAME ?= backend
-FRONTEND_CONTAINER_NAME ?= frontend
+BACKEND_CONTAINER_NAME ?= grocy-backend
+FRONTEND_CONTAINER_NAME ?= grocy-frontend
 POD_NAME ?= grocy-pod
-APP_DB_VOLUME_NAME ?= app-db
+APP_DB_VOLUME_NAME ?= grocy-app-db
 
 PLATFORM ?= linux/386 linux/amd64 linux/arm/v6 linux/arm/v7 linux/arm64/v8 linux/ppc64le linux/s390x