Add Grok as top level parser to be used with any plugin

[russorat]

Proposal:

Add GROK as a top level parser so that all plugins can take advantage of it. Currently it is only available for the logparser plugin. The specific ask was regarding the Kafka input.

Current behavior:

Grok parsing is only available for the logparser plugin

Desired behavior:

Grok parsing is available for all plugins.

Use case: [Why is this important (helps with prioritizing requests)]

Some users are pushing log messages from many machines into Kafka, and would like to add their grok patterns so that fields and tags are decoded automatically.