[tcp_uart][uart_tcp] Expose the no-arg load_settings() and mark UartTcp final (#20163)

esphome/components/tcp_uart/tcp_uart.h

@@ -44,6 +44,7 @@ class TcpUart : public uart::UARTComponent, public Component {
   bool is_connected() override { return this->link_.connected(); }
 #if defined(USE_ESP8266) || defined(USE_ESP32)
   void load_settings(bool dump_config) override {}
+  using UARTComponent::load_settings;  // also bring in the no-arg overload for convenience
 #endif
 
  protected:

esphome/components/uart_tcp/uart_tcp.h

@@ -14,7 +14,7 @@
 namespace esphome::uart_tcp {
 
 /// Copies raw bytes between one hardware UART and one TCP socket.
-class UartTcp : public Component, public uart::UARTDevice {
+class UartTcp final : public Component, public uart::UARTDevice {
  public:
   void set_host(const char *host) { this->link_.set_host(host); }
   void set_port(uint16_t port) { this->link_.set_port(port); }

tests/components/tcp_uart/test.esp32-idf.yaml

@@ -1,2 +1,10 @@
 packages:
   tcp_uart: !include common.yaml
+
+# load_settings() exists on ESP8266 and ESP32 only; both overloads must resolve.
+interval:
+  - interval: 60s
+    then:
+      - lambda: |-
+          id(tcp_uart_server).load_settings();
+          id(tcp_uart_server).load_settings(false);

tests/components/tcp_uart/test.esp8266-ard.yaml

@@ -1,2 +1,10 @@
 packages:
   tcp_uart: !include common.yaml
+
+# load_settings() exists on ESP8266 and ESP32 only; both overloads must resolve.
+interval:
+  - interval: 60s
+    then:
+      - lambda: |-
+          id(tcp_uart_server).load_settings();
+          id(tcp_uart_server).load_settings(false);