rename to fortify and restructure

More sandbox features will be added and this will no longer track ego's features and behaviour.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

internal/app/builder.go

@@ -0,0 +1,13 @@
+package app
+
+func (a *App) Command() []string {
+	return a.command
+}
+
+func (a *App) UID() int {
+	return a.uid
+}
+
+func (a *App) AppendEnv(k, v string) {
+	a.env = append(a.env, k+"="+v)
+}