[BUG] Need to check if 'ifconfig' is available or replace with 'ip add show'

**Describe the bug**
'ifconfig' got deprecated and soon we won't see it in many distro. I still see below error message in today's SLES 15. Can you check if waagent can substitutes 'ip address show' when no ifconfig command available in the system?

Error in waagent.log : 2019/11/18 19:58:00.744410 ERROR Daemon Command: [ifconfig -a], return code: [127], result: [/bin/sh: ifconfig: command not found]

Note: Please add some context which would help us understand the problem better
1. Provision a new SLES 15
2. Check the waagent log

**Distro and WALinuxAgent details (please complete the following information):**
- Distro and Version: SLES 15 (4.12.14-5.30-azure)
- WALinuxAgent version: WALinuxAgent-2.2.36 running on sles 15
Python: 3.6.8
Goal state agent: 2.2.36

**Additional context**
NA