system: move system access packages

These packages loosely belong in the "system" package and "system" provides high level wrappers for all of them.

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

system/dbus/export_test.go

@@ -0,0 +1,13 @@
+package dbus
+
+import (
+	"context"
+	"io"
+)
+
+// NewDirect returns a new instance of [Proxy] with its sandbox disabled.
+func NewDirect(ctx context.Context, final *Final, output io.Writer) *Proxy {
+	p := New(ctx, final, output)
+	p.useSandbox = false
+	return p
+}