Add CT Clamp component (#559)

* Add CT Clamp component

* Update lint

* Some more fixes

* Make updates to work as an analog sensor consumer

* Remove unused imports
Update lint suggestions

* Move setup_priority to header

* Remove unused calibration value

* Remove Unique ID

- Will be auto generated

* Update to use loop and not slow down main loop


Co-authored-by: Otto Winter <otto@otto-winter.com>

esphome/components/ct_clamp/ct_clamp_sensor.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/core/esphal.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/voltage_sampler/voltage_sampler.h"
+
+namespace esphome {
+namespace ct_clamp {
+
+class CTClampSensor : public sensor::Sensor, public PollingComponent {
+ public:
+  void update() override;
+  void loop() override;
+  void dump_config() override;
+  float get_setup_priority() const override { return setup_priority::DATA; }
+
+  void set_sample_duration(uint32_t sample_duration) { sample_duration_ = sample_duration; }
+  void set_source(voltage_sampler::VoltageSampler *source) { source_ = source; }
+
+ protected:
+  /// High Frequency loop() requester used during sampling phase.
+  HighFrequencyLoopRequester high_freq_;
+
+  /// Duration in ms of the sampling phase.
+  uint32_t sample_duration_;
+  /// The sampling source to read values from.
+  voltage_sampler::VoltageSampler *source_;
+
+  /** The DC offset of the circuit.
+   *
+   * Diagram: https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/interface-with-arduino
+   *
+   * This is automatically calculated with an exponential moving average/digital low pass filter.
+   *
+   * 0.5 is a good initial approximation to start with for most ESP8266 setups.
+   */
+  float offset_ = 0.5f;
+
+  float sample_sum_ = 0.0f;
+  uint32_t num_samples_ = 0;
+  bool is_sampling_ = false;
+};
+
+}  // namespace ct_clamp
+}  // namespace esphome