[Feat] Switch From seq.json File to Splunk Checkpoint Feature

[8ear]

Why

If you deploy your app with an deployment server, the deployment server replaces the whole app / ta folder to all heavy forwarder / search indexes / etc.. This replaces also the local folder in which the seq.json file is in place.

What

Remove the usage of external file for a sequence number and use the checkpoint function from the splunk python helper scripts.
https://docs.splunk.com/Documentation/AddonBuilder/2.2.0/UserGuide/PythonHelperFunctions

How

• Remove seq.json requirement
• Add checkpoint feature for sequence number
• Test if it works

[geertjanvdk]

This is not entirely correct. When an App is upgraded within Splunk, the /local folder is kept intact.
But yes, we should checkpoint to KV.

Note link:
https://docs.splunk.com/Documentation/AddonBuilder/3.0.2/UserGuide/PythonHelperFunctions