CLI: Refactor tests and config initialization

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/commands/config.go

@@ -0,0 +1,15 @@
+package commands
+
+import (
+	"github.com/urfave/cli"
+
+	"github.com/photoprism/photoprism/internal/config"
+	"github.com/photoprism/photoprism/internal/service"
+)
+
+// InitConfig initializes the command config.
+var InitConfig = func(ctx *cli.Context) (*config.Config, error) {
+	c := config.NewConfig(ctx)
+	service.SetConfig(c)
+	return c, c.Init()
+}