Load RubyGems extensions in the first place

This is not currently causing any issues, but I think the most correct
thing to do is that Bundler loads the extensions to RubyGems in the
first place, so that they are available from the beginning.

Author: deivid-rodriguez

bundler/lib/bundler.rb

@@ -1,13 +1,13 @@
 # frozen_string_literal: true
 
+require_relative "bundler/rubygems_ext"
 require_relative "bundler/vendored_fileutils"
 require "pathname"
 require "rbconfig"
 
 require_relative "bundler/errors"
 require_relative "bundler/environment_preserver"
 require_relative "bundler/plugin"
-require_relative "bundler/rubygems_ext"
 require_relative "bundler/rubygems_integration"
 require_relative "bundler/version"
 require_relative "bundler/current_ruby"