feat: add the ability to log into a registry on a per-app basis

Closes #5324

plugins/builder-dockerfile/builder-build

@@ -246,6 +246,9 @@ trigger-builder-dockerfile-builder-build() {
   done
 
   eval "$(config_export app "$APP")"
+  local DOCKER_CONFIG
+  DOCKER_CONFIG="$(fn-registry-docker-config "$APP")"
+  [[ -n "$DOCKER_CONFIG" ]] && export DOCKER_CONFIG
   "$DOCKER_BIN" image build "${DOCKER_BUILD_LABEL_ARGS[@]}" "${DOCKERFILE_ARGS[@]}" --tag $IMAGE .
 
   plugn trigger ports-set-detected "$APP" "$(fn-builder-dockerfile-get-detect-port-map "$APP" "$IMAGE" "$SOURCECODE_WORK_DIR/Dockerfile")"

plugins/builder-dockerfile/builder-release

@@ -29,6 +29,9 @@ trigger-builder-dockerfile-builder-release() {
     DOCKER_BUILD_ARGS+=("--platform=linux/amd64")
   fi
 
+  local DOCKER_CONFIG
+  DOCKER_CONFIG="$(fn-registry-docker-config "$APP")"
+  [[ -n "$DOCKER_CONFIG" ]] && export DOCKER_CONFIG
   if ! suppress_output "$DOCKER_BIN" image build "${DOCKER_BUILD_ARGS[@]}" $DOKKU_GLOBAL_BUILD_ARGS -f "$PLUGIN_AVAILABLE_PATH/builder-dockerfile/dockerfiles/builder-release.Dockerfile" --build-arg APP_IMAGE="$IMAGE" -t "$IMAGE" "$TMP_WORK_DIR"; then
     dokku_log_warn "Failure injecting docker labels on image"
     return 1