placeholderCharacter containing non special character as value causes issues

[GillesVercammen]

Is this a regression?
No

Description
ngx-mask provides a way to overwrite the default _ character as placeholder when showMaskTyped is true.
I now had the requirement to have this placeholderCharacter be a non-special character. a regular 'X'.
As of the docs, i didn't read anywhere whether this would cause issues or not.

But i soon noticed that use 'X' as a placeholderCharacter introduced some bugs.
First of all it added the character to the actual model, which it doesn't do for the special characters (even if dropSpecialCharacter=false). I would have expected to just never have the placeholderCharacter in the model.

2nd bug you can best see in my reproduction demo below. When i have a mask with 'X' as placeholderCharacter InputTransformFn, when i start typing with a lowercase character. It moves the cursor to the end of the input.
It works as expected when typing digits and uppercase characters. But when typing a lowercase character it has this weird behavior.

🔬 Minimal Reproduction
https://stackblitz-starters-st2qnr8f.stackblitz.io/
https://stackblitz.com/edit/stackblitz-starters-st2qnr8f?file=src%2Fmain.ts

So i'm not sure if this is an actual bug, or if the placeholderCharacter should just be restricted to only have special characters allowed?

EDIT:
I just noticed another problem in the normal behavior.
When i have the code as in the stackblitz with the * as placeholderCharacter and i fill in the whole mask.
then move my cursor to a specific character and type a lowercase character. The cursor again moves to the end. This does not happen for the uppercase and digits.