Function IsKeyChordPotentiallyCharInput

- We need this to filter some Shortcut() routes when an item e.g. an InputText() is active e.g. ImGuiKey_G won't be considered a shortcut when item is active, but ImGuiMod|ImGuiKey_G can be. - This is also used by UpdateInputEvents() to avoid trickling in the most common case of e.g. pressing ImGuiKey_G also emitting a G character.