Add telegram package (#4902)

Create starter script

Rubyize install lines

packages/telegram.rb

+require 'package'
+
+class Telegram < Package
+  description "Telegram is a messaging app with a focus on speed and security, it's super-fast, simple and free."
+  homepage 'https://telegram.org/'
+  version '2.5.1'
+  compatibility 'x86_64'
+  case ARCH
+  when 'x86_64'
+    source_url 'https://updates.tdesktop.com/tlinux/tsetup.2.5.1.tar.xz'
+    source_sha256 '939275a84498dedb1a33ac3f0242b0211548ddb087f9801518db92c5d6dc0151'
+  end
+
+  def self.build
+    system "cat <<'EOF'> telegram
+#!/bin/bash
+QT_QPA_PLATFORM=wayland-egl DISPLAY= WAYLAND_DISPLAY=wayland-0 Telegram \"\$@\"
+EOF"
+  end
+
+  def self.install
+    FileUtils.install 'Telegram', "#{CREW_DEST_PREFIX}/bin/Telegram", mode: 0755
+    FileUtils.install 'telegram', "#{CREW_DEST_PREFIX}/bin/telegram", mode: 0755
+  end
+
+  def self.postinstall
+    puts
+    puts "Type 'telegram' to get started.".lightblue
+    puts
+  end
+end