Test asset tag function of IPMI.
Test asset tag function of IPMI.

Test cases added:
    - Set Asset Tag With Valid String Length
    - Set Asset Tag With Invalid String Length
    - Set Asset Tag With Valid String Length Via REST

Resolves openbmc/openbmc-test-automation#775

Change-Id: I19a136548cf87e08a6a9a80ed97b8040f8e8e6db
Signed-off-by: Rahul Maheshwari <a806e6fd77e56dd64ff6084a06bbf3a5a70392ef@in.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation