Limit validation of Log Collections by default

[jautor]

Services with LogServices will likely have valid logs with perhaps hundreds of entries. We should check one LogEntry per Log and skip the rest for both performance and output brevity.

I believe that should be the default behavior, with an override to check all LogEntry resources.

Separately, an option to limit validation to the "first members" of each collection would also be useful for the same reason.

[jautor]

Also, a similar behavior should likely apply to "Sessions" (perhaps default is to look only at the current user session to avoid privilege errors?)