Simplify pipeline rule writing experience

## What?

This feedback is from HS-543762600
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A general thought regarding the question of extractors vs pipelines; I think extractors have been easier to get going for new users and hopefully you can add features to make pipeline rule development a little easier to get into for new users.
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## Why?

For users who are moving from extractors to a more prolific use of pipelines, as well as users new to Graylog, the pipeline writing process can be intimidated and complex. Unless they go through training, the most that folks can hope for is to stumble through the process by searching for information and performing copious amounts of copy pasta until they accomplish what they need to .

There are several approaches that we could take to simplify the process:

- Have an in-product pipeline walkthrough
- Have a more UI-driven approach to building a pipeline (e.g., drag and drop pipeline rule builder)
- Have a catalog of pre-written pipeline rules that are aimed at new users, or those who aren't quite sure what they want to do with their data

There probably other ways of simplifying the process, but those are the ones that immediately come to mind.