ModernTabs

General

• implemented a new system that makes it possible to render any sprite as your tab icon without it having to be an registered item in game
• implemented a new system for customizing the creative tab scrollbar (this was already possible on NeoForge, but not on Fabric. Therefore, it adds an cross-platform option to handle this) 
• cleaned up some parts of the code

Technical

• added a new ModernTabs.Builder which bundles nearly all customizable options for creative tabs in one place and therefore replaces the old system -> you can now use ModernTabs.builder(yourTab) to further customize your tab
• if you use this mod in your development environment, the example tab is now enabled by default