Message to Simulator Button in message view(s)

When viewing a message, it would me nice to be able to send this message to the processing pipeline simulator, similar to
"Test against stream" button for stream rules.

## What?
When pressing the button, the simulator view opens, with the message in Gelf format already in the raw message field, the gelf codec selected.

## Why?
Today I once again saw myself in the position where I had to debug a complex message, which led to me awkwardly coping from the message view the fields and the reformat everything into GELF by hand.

While this is not a daily occurence, it was not the first time and I needed something like this more often than the "Test against stream" functionality.

## Your Environment
* Graylog Version: 4.0.1+6a0cc0b