Custom fonts for text labels do not work for multiple labels

[brentru]

Providing add_text a custom font does not seem to track the label's index like other text properties do (color, scale, etc, https://github.com/adafruit/Adafruit_CircuitPython_MatrixPortal/blob/master/adafruit_matrixportal/matrixportal.py#L120).

The second time a user calls add_text, the _text_font property is changed to the latest text label's font.

In this example,

matrixportal.add_text(
    text_font=("/IBMPlexMono-Medium-24_jep.bdf"),
    text_position=((matrixportal.graphics.display.width // 4) - 1, (matrixportal.graphics.display.height // 3) - 1),
    text_color=0x800000,
)
matrixportal.preload_font("0123456789")

matrixportal.add_text(
    text_font=terminalio.FONT,
    text_position=(2, 25),
    text_color=0x000080,
    scrolling = True
)

The value of _text_font would be set as terminalio.FONT

This causes an issue in set_text where self._text_font is used to create the Label. The first label would be initialized with the second label's font
https://github.com/adafruit/Adafruit_CircuitPython_MatrixPortal/blob/master/adafruit_matrixportal/matrixportal.py#L282