Add load and loadAsync methods back to Loader

[Methuselah96]

Why

When writing code that should work with any loader, it's useful to have the load and loadAsync methods available on the Loader class. Since loadAsync is actually implemented in Loader, introducing generics, allows us to make sure the data types align.

What

Add TData and TUrl generics to Loader in order to redefined the load and loadAysnc methods in Loader.

Checklist

• Checked the target branch (current goes master, next goes dev)
• Added myself to contributors table
• Ready to be merged