Consider allowing PC to be passed into Handler

[thockin]

This would make bridging from slog a bit cleaner, rather than handlers doing their own unwinding.

[pohly]

I had considered this. It seems doable.

I did not pursue it further because it won't work with current LogSink implementations. If we expect implementations to be modified, wouldn't it be better to support slog directly?

[thockin]

#204

I did it and then realized exactrly what you said.

[pohly]

The alternative is an interface that is specific to slog:

// SlogSink is an interface that a LogSink can implement to support logging
// through the slog.Logger or slog.Handler APIs better. It then should
// also support special slog values like slog.Group.
type SlogSink interface {
	logr.LogSink

	Handle(ctx context.Context, record slog.Record) error
	WithAttrs(attrs []slog.Attr) SlogSink
	WithGroup(name string) SlogSink
}

I'll prepare a PR with that once #205 is merged.