added function to clear gui items

[Osanchez]

No description provided.

[zrdzn]

By looking at other methods that remove single items, I guess you are missing item removal from inventory.

triumph-gui/core/src/main/java/dev/triumphteam/gui/guis/BaseGui.java

Lines 256 to 282 in 49952b1

	/**
	* Removes the given {@link ItemStack} from the GUI.
	*
	* @param item The item to remove.
	*/
	public void removeItem(@NotNull final ItemStack item) {
	final Optional<Map.Entry<Integer, GuiItem>> entry = guiItems.entrySet()
	.stream()
	.filter(it -> it.getValue().getItemStack().equals(item))
	.findFirst();
	entry.ifPresent(it -> {
	guiItems.remove(it.getKey());
	inventory.remove(item);
	});
	}
	/**
	* Removes the {@link GuiItem} in the specific slot.
	*
	* @param slot The GUI slot.
	*/
	public void removeItem(final int slot) {
	validateSlot(slot);
	guiItems.remove(slot);
	inventory.setItem(slot, null);
	}

[Osanchez]

@zrdzn yea, you can itterate the map and remove items one by one. I just thought a clear would be cleaner