Add reset parameter

[brentru]

• Resets the RFM9x module before attempting to read the RFM9x RegVersion. Prevents chip from starting/reading from a bad state.
• Adds a deinit() method along with enter and exit methods for use with a context manager
• Examples have been changed to reflect the addition of the RST pin.
• Formatted file with Black

Tested on a Feather M4 with Radio FeatherWing. Test Harness for setting up (and tearing down) the SPI interface and lora object:

import time
import busio
import digitalio
import board
from adafruit_tinylora.adafruit_tinylora import TTN, TinyLoRa

# RFM9x Breakout Pinouts
cs = digitalio.DigitalInOut(board.D6) 
irq = digitalio.DigitalInOut(board.D5) 
rst = digitalio.DigitalInOut(board.D4)

# TTN Device Address, 4 Bytes, MSB
devaddr = bytearray([snip])

# TTN Network Key, 16 Bytes, MSB
nwkey = bytearray([snip])

# TTN Application Key, 16 Bytess, MSB
app = bytearray([snip])

ttn_config = TTN(devaddr, nwkey, app, country='US')

for i in range(0, 1001):
    print('init RFM9x and TinyLora...', i)
    spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
    lora = TinyLoRa(spi, cs, irq, rst, ttn_config)
    print('Sending Packet...')
    data = bytearray(b"\x43\x57\x54\x46")
    lora.send_data(data, len(data), lora.frame_counter)
    print('Packet Sent!')
    print('tearing down TinyLoRa..')
    lora.deinit()
    print('tearing down SPI..')
    spi.deinit()

Test Output (snipped):

init RFM9x and TinyLora... 329
Sending Packet...
Packet Sent!
tearing down TinyLoRa..
tearing down SPI..
init RFM9x and TinyLora... 330
Sending Packet...