[Feat] Publish TA in Splunkbase

[8ear]

Why

Currently the TA is only available through Github.com. This is not administrator friendly and is not the expectation of Splunk administrator. Because Splunk has his own app store: Splunkbase.
Updates work currently only on manual work and no information is send to people which have installed the TA.

What

Publish and update the TA via splunkbase.

How

• Modify the TA to be compatible to Splunkbase manual
• Package and publish the TA in Splunkbase

[geertjanvdk]

We will have both worlds:

• Through Splunkbase
• and through releases within GitHub: made easier in issue [Feat] Support Python v3.7+ to support Splunk v8 #10