[modbus_controller] Add assumed_state to switch (#8880)

Co-authored-by: Stanley Pinchak <stanley.pinchak@gmail.com>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/components/modbus_controller/switch/modbus_switch.cpp

@@ -19,6 +19,10 @@ void ModbusSwitch::setup() {
 }
 void ModbusSwitch::dump_config() { LOG_SWITCH(TAG, "Modbus Controller Switch", this); }
 
+void ModbusSwitch::set_assumed_state(bool assumed_state) { this->assumed_state_ = assumed_state; }
+
+bool ModbusSwitch::assumed_state() { return this->assumed_state_; }
+
 void ModbusSwitch::parse_and_publish(const std::vector<uint8_t> &data) {
   bool value = false;
   switch (this->register_type) {