Support Custom Fonts

[FoamyGuy]

Right now the library is made mainly for the built-in terminal.FONT. It would be nice to allow the user to set a custom font, and perhaps some ability to scale the emoji bitmaps internally so that it's possible to keep the size of the emoji roughly in line with different font sizes that maybe be possible with custom fonts.

[dglaude]

The documentation at https://docs.circuitpython.org/projects/display-emoji-text/en/latest/api.html#adafruit_display_emoji_text.EmojiLabel seems to say that there is a parameter ascii_font with a default value:

adafruit_display_emoji_text.EmojiLabel(text, scale=1, ascii_font=terminalio.FONT)

The code accept a font as parameter, but does not behave properly and is very slow.

Here is a test piece of code and matching result:

"""
Demonstration of EmojiLabel with non standard font.
"""

import time
import board
import displayio

from adafruit_bitmap_font import bitmap_font
from adafruit_display_emoji_text import EmojiLabel

# Text info
trivia_font = bitmap_font.load_font("/fonts/Arial-ItalicMT-17.bdf")
trivia_font.load_glyphs(
    b"abcdefghjiklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_- ().!?"
)

main_group = displayio.Group()
display = board.DISPLAY

emoji_lbl1 = EmojiLabel("🐍\n🐍   Circuit😎Python", scale=1, ascii_font=trivia_font)
emoji_lbl2 = EmojiLabel("🐍\n\n\n🐍   Circuit😎Python", scale=1)

main_group.append(emoji_lbl1)
main_group.append(emoji_lbl2)
display.root_group = main_group

while True:
    pass

I have the impression that character are aligned on the top, rather than to be aligned on the bottom.
So small letter are floating.

Also, this line of code is very slow (like multiple seconds):

emoji_lbl1 = EmojiLabel("🐍\n🐍   Circuit😎Python", scale=1, ascii_font=trivia_font)