Add more DTrace tooling

[leftwo]

Added a get-up-state bash and d scripts for looking at the sled overall and producing a high level summary.
This script will gather some selected dtrace stats for 10 seconds, then print out a summary.

In the first example here we have 3 unique propolis-server processes.
We print a line for each PID/Session (a single PID can have multiple sessions)

  PID  SESSION DS0 DS1 DS2   NEXT_JOB DELTA CONN   ELR   ELC   ERR   ERN
 9972 b5d1cbe7 ACT ACT ACT      65953    12    3     0     0     0     0
12059 69cc7aa8 ACT ACT ACT       2095     0    3     0     0     0     0
12059 924f18ed ACT ACT ACT       1444     0    3     0     0     0     0
12059 d7e7d0fd ACT ACT ACT      30292     0    3     0     0     0     0
12172 74ddab44 ACT ACT ACT     688093    83    3     0     0     0     0
12172 a151673e ACT ACT ACT       2198     0    3     0     0     0     0

I've hacked together a summary of the downstairs states into three letters.
Not all states have three letter summaries, but I've captured the common ones.

The DELTA is the number of jobs that went through this PID/Session in the 10 seconds we were watching.
CONN is number of times the upstairs has connected to a downstairs (the sum of all client connections).
ELR is extents that have been live repaired.
ELC is extents that were checked during LR, but no repair was needed.
ERR is extents that were reconcilied (happens on startup).
ERN is the remaining number of extents we need to reconcile.

Here is another example. In this case you can see that some extents were reconciled when propolis first started.

  PID  SESSION DS0 DS1 DS2   NEXT_JOB DELTA CONN   ELR   ELC   ERR   ERN
 9200 5827dcae ACT ACT ACT      15326     0    3     0     0     0     0
11977 9ab0865f ACT ACT ACT       1309     0    3     0     0     0     0
12595 4878f9f0 ACT ACT ACT      16944     0    3     0     0     0     0
13891 fb840f9f ACT ACT ACT  464968478 38777    3     0     0   400     0
13931 d5613d2e ACT ACT ACT      94948     0    3     0     0    24     0

This status script found the #1579 bug.
Updated upstairs_count.d to include barrier operations.