tailscale: Add tailssh server

protocol/tailscale/tailssh/session_android.go

@@ -0,0 +1,23 @@
+//go:build with_gvisor && android
+
+package tailssh
+
+import "github.com/sagernet/sing-box/adapter"
+
+func selectShellBackend(platformInterface adapter.PlatformInterface) shellBackend {
+	return &platformShellBackend{platform: platformInterface}
+}
+
+func CheckServerSupport(platformInterface adapter.PlatformInterface) (string, error) {
+	if platformInterface != nil {
+		err := platformInterface.CheckPlatformShell()
+		if err == nil {
+			return "", nil
+		}
+	}
+	return "running without root, SSH sessions are limited to the sing-box user", nil
+}
+
+func lookupSFTPServer(platformInterface adapter.PlatformInterface) (string, error) {
+	return platformInterface.LookupSFTPServer()
+}