Added dpkg.rb to Packages directory. (#2327)

* Added dpkg.rb to Packages directory.

* Added alias to fix issue of dpkg installing packages on root directory.

* Change double quote and backslash to single quote "just in case"

* Fixed file formatting errors

* No need to remount ~/ as execute

* Removed unnecessary dependencies

* Added echo to ~/.bashrc line to make alias persistent

* Fixed error in which ~/.bashrc line was quoted

* Reverting changes from previous commit

* Changed default dpkg root directory from /usr/local to \#{CREW_PREFIX}

* Removed #{CREW_PREFIX} tag, single quotes necessary

* Made dpkg more universal, including support for zsh and fish

* Added symlink from /usr/ to /usr/local/usr

* Added diversity for architectues, packages now automatically install to /usr/local. Close to final product, still working out the
kinks.

* Reduced size, added symlink from /usr/local to /usr/local/usr/local. All good and ready to go!

* Replaced exact paths with environment variables.

* Fixed errors on file layout (Hopefully!)

* Fixed file format

* Added line to touch /var/lib/dpkg/status.

* Fixed issue where dpkg status file wasn't being tracked

* Too many changes to be listed in a commit. See for yourself [here.](https://github.com/JL2210/chromebrew/tree/dpkg/packages/dpkg.rb)

* Moved line to touch dpkg status file to postinstall.

* Added more thorough explanation on how to install packages.

* Changed root install directory to /usr/local.
Fixed issue where the dpkg status file would be overwritten during upgrade.
Removed annoying dependency check.

* Installing dpkg now works if you haven't installed it before

packages/dpkg.rb

+require 'package'
+
+class Dpkg < Package
+  description 'A medium-level package manager for Debian'
+  homepage 'https://anonscm.debian.org/git/dpkg/'
+  version '1.19.0.5-test'
+  source_url 'https://salsa.debian.org/dpkg-team/dpkg/-/archive/1.19.0.5/dpkg-1.19.0.5.tar.gz'
+  source_sha256 'd38308afcd5d7896bbd1f946875b90f9d8510a8a96b44e4f14e781285e5d9641'
+
+  depends_on 'icu4c' => :build
+
+  def self.build
+    system "git clone https://salsa.debian.org/dpkg-team/dpkg.git"
+    Dir.chdir ("dpkg") do
+      system "git checkout 1.19.0.5"
+      system "autoreconf -i -f"
+      system "./configure --libdir=#{CREW_LIB_PREFIX} --prefix=#{CREW_PREFIX}"
+      system "make"
+    end
+  end
+
+    def self.preinstall
+  if File.exists? "#{CREW_PREFIX}/var/lib/dpkg/status" then
+      system "mv #{CREW_PREFIX}/var/lib/dpkg/status #{CREW_PREFIX}/var/lib/dpkg/status.old"
+    end
+  end
+  def self.install
+    Dir.chdir ("dpkg") do
+      system "make install DESTDIR=#{CREW_DEST_DIR}"
+      system "mkdir -p #{CREW_DEST_PREFIX}/usr/"
+      system "ln -s #{CREW_PREFIX} #{CREW_DEST_PREFIX}/usr/local"
+      system "mkdir -p #{CREW_DEST_PREFIX}/var/lib/dpkg/"
+      system "touch #{CREW_DEST_PREFIX}/var/lib/dpkg/status"
+    end
+    Dir.chdir ("#{CREW_DEST_PREFIX}/bin") do
+      system 'mv dpkg dpkg-run'
+      system "echo '#!/bin/bash' > dpkg"
+      system "echo 'dpkg-run --force-depends --root=#{CREW_PREFIX} \"$@\"' >> dpkg"
+      system 'chmod a+x dpkg'
+    end
+  end
+      def self.postinstall
+    if File.exists? "#{CREW_PREFIX}/var/lib/dpkg/status.old" then
+      system "cat #{CREW_PREFIX}/var/lib/dpkg/status.old >> #{CREW_PREFIX}/var/lib/dpkg/status"
+      system "rm #{CREW_PREFIX}/var/lib/dpkg/status.old"
+    end
+  end
+end