Reimplement JEI integration

[mezz]

Hi @Technici4n, figured I'd return the favor for

• Switch to new ModDevGradle plugin mezz/JustEnoughItems#3739

I got a request for this:

• [Suggestion]: Not exactly for JEI, but a "Powah JEI Integration" mezz/JustEnoughItems#3760

This also resolves

• JEI support is missing in 1.21.1 Neoforge #186

and thought it would be best to reimplement the integration here because it's pretty basic.

[Technici4n]

Thanks!