vmui/logs: add markdown support

[Loori-R]

Describe Your Changes

Add support for markdown format and emoji for the _msg field in the "Group" view.
Add markdown rendering toggle. Disabled by default. Value is stored in localStorage.

before
after

Checklist

The following checks are mandatory:

• My change adheres VictoriaMetrics contributing guidelines.

[dmitryk-dk]

LGTM!

[zekker6]

Do I understand it correctly that current implementation enables markdown rendering by default and there is no way to disable it?
I'm afraid that there will definitely be use-cases when this will render markdown at places where it was just using *, _ or other special characters in markdown, so it would be great to have a toggle to disable this.

[Loori-R]

@zekker6, good idea, I'll add a switch.
Should we disable it by default?

[zekker6]

@zekker6, good idea, I'll add a switch. Should we disable it by default?

From my experience, it's better to disable this by default as most logs do not contain markdown at all.

It would be great if we could enable this by default for the play environment thought (or have some kind of automatic detection logic in place).