HAL renaming & relocation (#215)

Implemented more consistent naming:
- Moved all HAL devices into their own namespace (and related folder)
- Post-fixed all HAL device names with "Device"

TactilityHeadless/Include/Tactility/hal/display/DisplayDevice.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include "../Device.h"
+
+#include <lvgl.h>
+
+namespace tt::hal::touch {
+class TouchDevice;
+}
+
+namespace tt::hal::display {
+
+class DisplayDevice : public Device {
+
+public:
+
+    Type getType() const override { return Type::Display; }
+
+    virtual bool start() = 0;
+    virtual bool stop() = 0;
+
+    virtual void setPowerOn(bool turnOn) {}
+    virtual bool isPoweredOn() const { return true; }
+    virtual bool supportsPowerControl() const { return false; }
+
+    virtual std::shared_ptr<touch::TouchDevice> _Nullable createTouch() = 0;
+
+    /** Set a value in the range [0, 255] */
+    virtual void setBacklightDuty(uint8_t backlightDuty) { /* NO-OP */ }
+    virtual bool supportsBacklightDuty() const { return false; }
+
+    /** Set a value in the range [0, 255] */
+    virtual void setGammaCurve(uint8_t index) { /* NO-OP */ }
+    virtual uint8_t getGammaCurveCount() const { return 0; };
+
+    /** After start() returns true, this should return a valid pointer until stop() is called and returns true */
+    virtual lv_display_t* _Nullable getLvglDisplay() const = 0;
+};
+
+} // namespace tt::hal::display