Font Library: Add an ability to replace font

[oglekler]

Instead of the error or notice that the font already exists, the font library should allow replacing the font. Sometimes a font can be corrupted for some reason, and you need to update it. So, the better flow should be to ask the users if they want to replace the font(s).

[youknowriad]

Given that it's already possible to delete uploaded fonts to replace them, I think this enhancement can be considered for 6.6 or later.