This PR makes `#guard_msgs` to treat `trace` messages separate from
`info`, `warning` and `error`. It also introduce the ability to say
`#guard_msgs (pass info`, like `(drop info)` so far, and also adds
`(check info)` as the explicit form of `(info)`, for completeness.
Fixes#8266
This PR makes the server consistently not report newlines between trace
nodes to the info view, enabling it to render them on dedicates lines
without extraneous spacing between them in all circumstances.
The info view code will separately need to be adjusted to this new
behavior, until then this change will make adjacent trace node leafs
consistently be rendered *on the same line* if there is sufficient
space. The cmdline should be unaffected in any case.
