Decouple bin/compile and bin/install from lib/

This commit duplicates a small amount of Ruby code that is run at build
or install time. Over time, it would be nice to remove the dependency
on Ruby for these steps, but the focus right now is on run-time.

We'll be removing lib/* from gitlab-shell very soon, and these commands
need to keep working when we do.

bin/install

 #!/usr/bin/env ruby
 
-require_relative '../lib/gitlab_init'
-
-#
-# GitLab shell, invoked from ~/.ssh/authorized_keys
-#
+# Load ROOT_PATH and access the minimum necessary config file
+require_relative '../support/go_build'
+require_relative '../support/gitlab_config'
 
 config = GitlabConfig.new
 key_dir = File.dirname("#{config.auth_file}")

support/gitlab_config.rb

+require 'yaml'
+
+class GitlabConfig
+  attr_reader :config
+
+  def initialize
+    @config = YAML.load_file(File.join(ROOT_PATH, 'config.yml'))
+  end
+
+  def auth_file
+    @config['auth_file'] ||= File.join(Dir.home, '.ssh/authorized_keys')
+  end
+end

support/go_build.rb

@@ -2,8 +2,8 @@
 
 require 'fileutils'
 
-# This will set the ROOT_PATH variable
-require_relative '../lib/gitlab_init'
+# Determine the root of the gitlab-shell directory
+ROOT_PATH = ENV.fetch('GITLAB_SHELL_DIR', File.expand_path('..', __dir__))
 
 module GoBuild
   GO_DIR = File.join(ROOT_PATH, 'go')