Add support for STS3x Temperature sensors (#669)

* Add support for Sensirion STS3x Temperature sensors

* Removed humidty reading from STS3x sensor

* Fixed line error and operand error

* Fixed syntax

* Add test snippet for STS3x sensor

* Clean up

* #550 Proactive fix for STS3x component reporting WARNING status and reinitialzing similar to SHT3xd

* Flattened config.

* Fixed missing temperature unit

* Code formatting

* Added marking for future commands

* Cleanup

* Removed whitespace

* Cleanup

* Cleanup

esphome/components/sts3x/sts3x.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/i2c/i2c.h"
+
+namespace esphome {
+namespace sts3x {
+
+/// This class implements support for the ST3x-DIS family of temperature i2c sensors.
+class STS3XComponent : public sensor::Sensor, public PollingComponent, public i2c::I2CDevice {
+ public:
+  void setup() override;
+  void dump_config() override;
+  float get_setup_priority() const override;
+  void update() override;
+
+ protected:
+  bool write_command_(uint16_t command);
+  bool read_data_(uint16_t *data, uint8_t len);
+};
+
+}  // namespace sts3x
+}  // namespace esphome