Allow `TextBox` to specify type of text being input

[frenzibyte]

Also has the bonus feature of allowing password managers (e.g. 1Password) to be integrated with the game, by specifying the text input type as Username/Password in the textboxes. Unfortunately it's still quite broken in SDL but should be fixable (see https://github.com/libsdl-org/SDL/pull/11406#discussion_r1827411417).

Since text input types are now identifiable with the new TextInputType field, I've applied a refactor on the TextBox classes to respect the type at a TextBox level w.r.t. certain functionalities such as clipboard exporting, key event logging, character display, etc. This includes removing BasicPasswordTextBox entirely as its behaviour can be achieved by simply:

new BasicTextBox
{
    InputProperties = new TextInputProperties(TextInputType.Password, allowIme: false)
}

I've gone for this refactor as it didn't sit well for me how these implementations still exist while there is now a new field specifying the type of text input.

[bdach]

Compilation failures here

[frenzibyte]

Noticed, fixed.