remove old bs code, start getting ready for freebsd and openbsd support

Overlord-Client/cmd/agent/persistence/persistence_default.go

@@ -0,0 +1,21 @@
+//go:build !windows && !linux && !darwin
+
+package persistence
+
+import "fmt"
+
+func install(_ string) error {
+	return fmt.Errorf("persistence is not implemented on this platform")
+}
+
+func configure(_ string) error {
+	return fmt.Errorf("persistence is not implemented on this platform")
+}
+
+func getTargetPath() (string, error) {
+	return "", fmt.Errorf("persistence is not implemented on this platform")
+}
+
+func uninstall() error {
+	return nil
+}