This attempts to solve #55

It turned out there were a few issues with the existing handling of anchored position leading to it not working correctly with scale.

• As noted on a comment in anchor_point and anchored_position do not work well with scale #55 the scale parameter in __init__() was actually belonging to the super class Group which does allow it to visually scale the text properly. But Label itself was not remembering or doing anything with the scale.

• The math in the anchored_position setter was taking into account the current (x, y) position of the label when determining the new one. But I don't think this is needed, the only things needed to determine the new position should be: the new desired coordinates, the anchor_point, and the width and height.

These changes resolve those issues by keeping the scale in self._scale and accounting for it when setting the anchored_position. As well as removing the unneeded referencing of the previous x,y position during calculations.

Changes were tested with this code:

import terminalio, displayio, board
from adafruit_display_text import label
text_area = label.Label(
    terminalio.FONT,
    text="Scale!", scale=5, color=0xc0c0c0, 
    background_color=0x0000FF
)
text_area.anchor_point = (0,0)
board.DISPLAY.show(text_area)
text_area.anchored_position = (0,0)  ### expectation is text will be on screen at top left
while True:
    pass

After these changes the label in this script is now positioned properly in the top left corner of the screen.

I also tested with the display_text_anchored_position.py example and it seems to still be working properly after these changes.