[switch] Use C++17 nested namespace syntax (#14241)

esphome/components/switch/binary_sensor/switch_binary_sensor.cpp

@@ -1,8 +1,7 @@
 #include "switch_binary_sensor.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace switch_ {
+namespace esphome::switch_ {
 
 static const char *const TAG = "switch.binary_sensor";
 
@@ -13,5 +12,4 @@ void SwitchBinarySensor::setup() {
 
 void SwitchBinarySensor::dump_config() { LOG_BINARY_SENSOR("", "Switch Binary Sensor", this); }
 
-}  // namespace switch_
-}  // namespace esphome
+}  // namespace esphome::switch_

esphome/components/switch/binary_sensor/switch_binary_sensor.h

@@ -4,8 +4,7 @@
 #include "esphome/core/component.h"
 #include "esphome/components/binary_sensor/binary_sensor.h"
 
-namespace esphome {
-namespace switch_ {
+namespace esphome::switch_ {
 
 class SwitchBinarySensor : public binary_sensor::BinarySensor, public Component {
  public:
@@ -17,5 +16,4 @@ class SwitchBinarySensor : public binary_sensor::BinarySensor, public Component
   Switch *source_;
 };
 
-}  // namespace switch_
-}  // namespace esphome
+}  // namespace esphome::switch_