feat: allow plugins to have a custom UI

[robertsLando]

This can be handled by creating a method on plugins like getUIConfig that will return a configuration like:

{
	"tabs": [
		{
			"title": "XXX",
			"tabIcon": "mdi-xxx",
			"path": "/my-plugin/ui"
		}
	]
}

Based on active plugins ZUI will add required tabs on left nav and when clicking on the tab show an iframe pointing to path specified

This could help implementing #3887