Support changing menu height

LibEditMode.lua

@@ -345,6 +345,7 @@ Depending on the setting type there are additional required and optional entries
 |:----------|:----------------------------------------------------------------------------------------------------------------------|:---------|:---------|
 | values    | indexed table containing [DropdownOption](#dropdownoption)s                                                           | table    | no       |
 | generator | [Dropdown `SetupMenu` "generator" (callback)](https://warcraft.wiki.gg/wiki/Patch_11.0.0/API_changes#New_menu_system) | function | no       |
+| height    | max height of the menu                                                                                                | integer  | no       |
 
 - Either `values` or `generator` is required, the former for simple menues and the latter for complex ones.
     - They are not exclusive, but `generator` takes precedence (e.g. `values` will be available but not used).

widgets/dropdown.lua

@@ -24,6 +24,10 @@ function dropdownMixin:Setup(data)
 		end)
 	elseif data.values then
 		self.Dropdown:SetupMenu(function(_, rootDescription)
+			if data.height then
+				rootDescription:SetScrollMode(data.height)
+			end
+
 			for _, value in next, data.values do
 				if value.isRadio then
 					rootDescription:CreateRadio(value.text, get, set, {