logging: log: add LOG_WRN_ONCE

[JordanYates]

Add an equivalent to the linux WARN_ONCE macro. This is intended for
use when the developer should be notified of an event, but may occur a
multitude of times in quick succession.

Using LOG_WRN could result in either cluttered logs or recursive
logging (i.e. in serial drivers).

Proposed in the discussion of #65112

[cfriedt]

LGTM - I tossed around a similar rate-limit debug variant at one point.

[nordic-krch]

Long time ago there was #41783 but author dropped it and it never get in. There we had LOG_<lvl>_N(n, ...) which was more flexible and supported all severity levels maybe it would be good to resurrect that approach instead?

[JordanYates]

Long time ago there was #41783 but author dropped it and it never get in. There we had LOG_<lvl>_N(n, ...) which was more flexible and supported all severity levels maybe it would be good to resurrect that approach instead?

I don't mind if that is the approach you want to go with, but I won't be resurrecting it.

IMO only LOG_LEVEL_WRN really makes sense for this macro anyway. DBG should always print, ERR is fatal, so likely won't happen again anyway, and INF is normal operation so shouldn't be spamming the logs in any case. WRN is uniquely "user should be notified, the event is unusual, but because its only a warning, may occur many times in quick succession".