Added Pop!_OS as a Ubuntu derivative

[shombando]

What does this PR do?

This PR adds support for Pop!_OS as an Ubuntu derivative. Only added 22 as a variant of Ubuntu 22.04 since that's all I can test, other versions should work equally well.

What issues does this PR fix or reference?

No open issues

Previous Behavior

bootstrap script failed with the following message:

 *  INFO: Running version: 2022.10.04
 *  INFO: Executed by: sh
 *  INFO: Command line: '/tmp/bootstrap-salt.sh '

 *  INFO: System Information:
 *  INFO:   CPU:          GenuineIntel
 *  INFO:   CPU Arch:     x86_64
 *  INFO:   OS Name:      Linux
 *  INFO:   OS Version:   5.19.0-76051900-generic
 *  INFO:   Distribution: Pop 22.04

 *  INFO: Installing minion
 *  INFO: Found function config_salt
 *  INFO: Found function preseed_master
 *  INFO: Found function daemons_running
 * ERROR: No dependencies installation function found. Exiting...

New Behavior

Salt installation is completed successfully

 *  INFO: Running install_ubuntu_stable_post()
 *  INFO: Running install_ubuntu_check_services()
 *  INFO: Running install_ubuntu_restart_daemons()
 *  INFO: Running daemons_running()
 *  INFO: Salt installed!