Fix ATs to classes with implicit constructors and add more validation

[Matyrobbrt]

• inject constructors with the old class access level when ATs target classes with implicit constructors (as, according to the JLS, implicit constructors follow the access level of their owner)
• prevent ATing enum constructors to public or protected
• prevent narrowing access, fixes AccessTransformer can narrow access in dev #11
• error when a record is AT'd without its constructor being AT'd too

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: c23831e8a0858ce83ac6c77933d0e208f5197971.

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged.jst:jst-cli:1.0.51-pr-21-more-validation
• 📦 net.neoforged.jst:jst-cli-bundle:1.0.51-pr-21-more-validation

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 #21' // https://github.com/neoforged/JavaSourceTransformer/pull/21
        url 'https://prmaven.neoforged.net/JavaSourceTransformer/pr21'
        content {
            includeModule('net.neoforged.jst', 'jst-cli')
            includeModule('net.neoforged.jst', 'jst-cli-bundle')
        }
    }
}