Visual indicator of additional lines in multiline message row

## What?

In older versions of Graylog there was a visual indicator (gradually fading lines of text) that a message table row contained a multiline message with more lines. This is a request to restore that design, or implement some other suitable indicator, for view-based message tables.

## Why?

When troubleshooting it's helpful to be able to quickly identify whether a multiline message contains additional lines. For example, ignoring that it's a predictable stack trace, how many lines does the first message in the image below actually have? 4? 50? I'd have to expand the message row and navigate down to the `message` field to find out.


## Your Environment

* Graylog Version: ~~3.3.2~~ 4.2.0
* Browser version: Firefox ~~78~~ 93