Widget: Message table with group function

## What?
Be able to create a message table that has the option to display messages not only sorted but also grouped by specific parameters.

Similar to the aggregation page but with a message table that show log lines.

## Why?
When you have logs from multiple systems or applications that have a connection - like a transaction or user-id - you want to show all messages that are sharing the same information together.

This allows you to display all messages together that belong to the same transaction or action in your environment. What would make Graylog be able to show process logs grouped together and create more value out of having all central.

The current solution is to create a dashboard with parameters that you need to insert the transaction ID and get overview of everything that is included. This feature would allow to get an overview without knowing the uuid upfront.