internal: move shim and init into app

This structure makes more sense, as both processes are part of an app's lifecycle.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/start.go

@@ -10,8 +10,8 @@ import (
 	"time"
 
 	"git.gensokyo.uk/security/fortify/helper"
+	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
 	"git.gensokyo.uk/security/fortify/internal/state"
 	"git.gensokyo.uk/security/fortify/internal/system"
 )