cmd: refactoring Run function

So it's easier, more clear, more isolation between code on non-mobile
and mobile platforms.

cmd/cli/library.go

@@ -1,5 +1,7 @@
 package cli
 
+// AppCallback provides hooks for injecting certain functionalities
+// from mobile platforms to main ctrld cli.
 type AppCallback struct {
 	HostName   func() string
 	LanIp      func() string
@@ -7,6 +9,7 @@ type AppCallback struct {
 	Exit       func(error string)
 }
 
+// AppConfig allows overwriting ctrld cli flags from mobile platforms.
 type AppConfig struct {
 	CdUID   string
 	HomeDir string