Update packages.apt

[adlarkin]

A lot of the Ignition repositories are transitioning towards instructing users to use a repository's *packages.apt files to install build dependencies (for example, ign-gazebo). In case users want to install all of the Ignition build dependencies in a single pass via a command like this, we should make sure things like cmake (and make) get installed so that users have no issues when using ign-cmake.

I also added in build-essential because this will guarantee that gcc, g++, and make are installed on Ubuntu Bionic and Focal - this is important in case users decided to use the --no-install-recommends flag when installing packages listed in the *packages.apt files (I ran a test with the ubuntu:focal Docker image and noticed that make wasn't installed even after installing all Ignition Binaries and other packages in Ignition's *packages.apt files. Including build-essential fixed this for me):

adl-ws@96bdcbfc1916:~/ws$ apt-cache depends build-essential
build-essential
 |Depends: libc6-dev
  Depends: <libc-dev>
    libc6-dev
  Depends: gcc
  Depends: g++
  Depends: make
    make-guile
  Depends: dpkg-dev

Signed-off-by: Ashton Larkin ashton@openrobotics.org