app: integrate fsu

This removes the dependency on external user switchers like sudo/machinectl and decouples fortify user ids from the passwd database.

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

internal/state/state.go

@@ -33,8 +33,6 @@ type State struct {
 	// capability enablements applied to child
 	Capability system.Enablements
 
-	// user switch method
-	Method string
 	// full argv whe launching
 	Argv []string
 	// process start time