Adding I2S examples

Adding I2S examples for the Metro M7 guide

Metro_M7_Examples/I2S_Tone/code.py

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+# SPDX-FileCopyrightText: 2021 Kattni Rembor for Adafruit Industries
+# SPDX-License-Identifier: MIT
+"""
+CircuitPython I2S Tone playback example.
+Plays a tone for one second on, one
+second off, in a loop.
+Remove this line and all of the following docstring content before submitting to the Learn repo.
+Update the three I2S pins to match the wiring chosen for the microcontroller. If you are unsure of
+a proper I2S pin combination, run the pin combination script found here:
+https://adafru.it/i2s-pin-combo-finder
+Update the following pin names to a viable pin combination:
+* BIT_CLOCK_PIN
+* WORD_SELECT_PIN
+* DATA_PIN
+"""
+import time
+import array
+import math
+import audiocore
+import board
+import audiobusio
+
+audio = audiobusio.I2SOut(board.D10, board.D9, board.D12)
+
+tone_volume = 0.1  # Increase this to increase the volume of the tone.
+frequency = 440  # Set this to the Hz of the tone you want to generate.
+length = 8000 // frequency
+sine_wave = array.array("h", [0] * length)
+for i in range(length):
+    sine_wave[i] = int((math.sin(math.pi * 2 * i / length)) * tone_volume * (2 ** 15 - 1))
+sine_wave_sample = audiocore.RawSample(sine_wave)
+
+while True:
+    audio.play(sine_wave_sample, loop=True)
+    time.sleep(1)
+    audio.stop()
+    time.sleep(1)

Metro_M7_Examples/I2S_Wav/code.py

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+# SPDX-FileCopyrightText: 2021 Kattni Rembor for Adafruit Industries
+# SPDX-License-Identifier: MIT
+"""
+CircuitPython I2S WAV file playback.
+Plays a WAV file once.
+
+Remove this line and all of the following docstring content before submitting to the Learn repo.
+
+Update the three I2S pins to match the wiring chosen for the microcontroller. If you are unsure of
+a proper I2S pin combination, run the pin combination script found here:
+https://adafru.it/i2s-pin-combo-finder
+
+Update the following pin names to a viable pin combination:
+* BIT_CLOCK_PIN
+* WORD_SELECT_PIN
+* DATA_PIN
+"""
+import audiocore
+import board
+import audiobusio
+
+audio = audiobusio.I2SOut(board.D10, board.D9, board.D12)
+
+with open("StreetChicken.wav", "rb") as wave_file:
+    wav = audiocore.WaveFile(wave_file)
+
+    print("Playing wav file!")
+    audio.play(wav)
+    while audio.playing:
+        pass
+
+print("Done!")