Merge SPI into loader sourceset

[Technici4n]

The separation does not bring much to the table, and is preventing us from cleaning up some APIs. For example, any mod language provider must instantiate ModContainer, and therefore must always depend on FML.

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: 01b2d387d71f3c24e6bc805c326fd3f97c69ab49.

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged.fancymodloader:loader:3.0.11-pr-109-merge-spi
• 📦 net.neoforged.fancymodloader:earlydisplay:3.0.11-pr-109-merge-spi

Repository Declaration

In order to use the artifacts published by the PR, add the following repository to your buildscript:

repositories {
    maven {
        name 'Maven for PR #109' // https://github.com/neoforged/FancyModLoader/pull/109
        url 'https://prmaven.neoforged.net/FancyModLoader/pr109'
        content {
            includeModule('net.neoforged.fancymodloader', 'loader')
            includeModule('net.neoforged.fancymodloader', 'earlydisplay')
        }
    }
}