MINOR: debug: relax access restrictions on "debug dev hash" and "memstats"

MINOR: debug: relax access restrictions on "debug dev hash" and "memstats"

These two have absolutely zero impact on the process and do not need to
be restricted to the expert mode. The first one calculates a string hash
that can be used by anyone when checking a dump; the second one may be
used by anyone tracking a memory leak, and is cumbersome to use due to
the "expert-mode on" that needs to be prepended. In addition this gives
bad habits to users and needlessly taints the process. So let's drop
this restriction for these two commands.