[FL-1616] RFID: fix HID emulation (#610)

* Rfid: fixed HID emulation by adding zero pulse every 4 bits
* Rfid: HID emulation fixed with DSP based FSK oscillator.

applications/lfrfid/helpers/osc-fsk.h

@@ -0,0 +1,30 @@
+#pragma once
+#include <stdint.h>
+
+/**
+ * This code tries to fit the periods into a given number of cycles (phases) by taking cycles from the next cycle of periods.
+ */
+class OscFSK {
+public:
+    /**
+     * Get next period
+     * @param bit bit value
+     * @param period return period
+     * @return bool whether to advance to the next bit
+     */
+    bool next(bool bit, uint16_t* period);
+
+    /**
+     * FSK ocillator constructor
+     * 
+     * @param freq_low bit 0 freq
+     * @param freq_hi bit 1 freq
+     * @param osc_phase_max max oscillator phase
+     */
+    OscFSK(uint16_t freq_low, uint16_t freq_hi, uint16_t osc_phase_max);
+
+private:
+    const uint16_t freq[2];
+    const uint16_t osc_phase_max;
+    int32_t osc_phase_current;
+};