Add Parse_Headers Method

[brentru]

Add method for parsing the header portion of an HTTP request/response from the socket.

Previous implementation in ESP32SPI_Requests module:
https://github.com/adafruit/Adafruit_CircuitPython_ESP32SPI/blob/c15e8fd9c0e53bb7e0ee2f1dd105cc09a7e70b7d/adafruit_esp32spi/adafruit_esp32spi_requests.py#L223

Affects ESP32SPI WSGI Server: adafruit/Adafruit_CircuitPython_ESP32SPI#62

[siddacious]

fixed via PR #5