Add CLI option to install client

[Matyrobbrt]

Add the --install-client CLI option that installs a client profile.
Since Neo doesn't need to make money through ads, 3rd parties are free to automate its installation.
This was tested by bumping the installer version in NeoGradle to net.neoforged:legacyinstaller:3.0.+.

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: 1bcef870b5f850b53c92d876cc0b49bda6077dcf.

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged:legacyinstaller:3.0.4-pr-1-client-cli-option

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 #1' // https://github.com/neoforged/LegacyInstaller/pull/1
        url 'https://prmaven.neoforged.net/LegacyInstaller/pr1'
        content {
            includeModule('net.neoforged', 'legacyinstaller')
        }
    }
}