[Feature Request 2985] Custom username editor

[edonaHajredinaj]

Adds Feature Request 2985, Added a custom username editor so that users can hide their username if someone looks at their phone screen.

[TacoTheDank]

@edonaHajredinaj Just a few nitpicks I have: please make openDialog private and rename it to fakenameDialog, and also replace .equals("") with .isEmpty(). Other than that, it looks good. Thank you very much for your contribution! :)

[TacoTheDank]

@edonaHajredinaj Any updates?

[TacoTheDank]

Guess I'll do it myself then...

[TacoTheDank]

@edonaHajredinaj No worries, I've already done it :)

[Alexendoo]

Thanks for the PR, just some R.string.* changes needed (allows them to be translated into different languages)

[ccrama]

I've updated the string resources, we should use the AlertDialogWrapper for better theming of this popup