[FEATURE] Publicize IsInputBlocked() method (GUIManager)

[aaron01-dev]

User Story
As a dev I want to make a condition to check for when the input is blocked so that my mod's UI (which is triggered by inputs) won't get triggered whenever something happens like typing in chat or keyboard controls from somewhere else.
but I'd have to copy the entire flag Valheim uses.
bool flag = (Chat.instance == null || !Chat.instance.HasFocus()) && !Console.IsVisible() && !TextInput.IsVisible() && !Menu.IsVisible() && !InventoryGui.IsVisible();

Envisioned Solution
Publicize IsInputBlocked()