move apis into rom/modules/main for shell compatibility

sys/modules/opus/ui/components/Tab.lua

@@ -0,0 +1,12 @@
+local class = require('opus.class')
+local UI    = require('opus.ui')
+
+local colors = _G.colors
+
+UI.Tab = class(UI.ActiveLayer)
+UI.Tab.defaults = {
+	UIElement = 'Tab',
+	tabTitle = 'tab',
+	backgroundColor = colors.cyan,
+	y = 2,
+}