Add custom formatting for string fields.

[PhaedrusTheGreek]

It would be nice if you could add custom formatting for string fields, similar to how it is done with numeric fields today. Desired behaviour is to be able to use regex matches as conditions, and apply field formatting such as colouring, or anything else that might be possible.

Very similar to request in #1304

[snelyuibn]

I need it too.

[pemontto]

👍

[jjdepaul]

Yes - we are looking forward to that feature being available.

[marcelhallmann]

We also need such a feature!

[marcelhallmann]

Are there any news on this issue?

[prabhuramsoft]

I need it too. when it will be avail & how to use it?

[s-trooper]

+1 highlighting log severity would be nice

[Bargs]

Closing this in favor of #6537 since it is more concrete and has an active PR being worked