Add new orchestrator capacities metric

[mjh1]

What does this pull request do? Explain your changes. (required)

Specific updates (required)

How did you test each of these updates (required)

Does this pull request close any open issues?

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 12 lines in your changes missing coverage. Please review.

Project coverage is 57.38314%. Comparing base (aad1a23) to head (8b251c8).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
server/broadcast.go	0.00000%	8 Missing ⚠️
monitor/census.go	69.23077%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3205         +/-   ##
===================================================
- Coverage   57.40145%   57.38314%   -0.01831%     
===================================================
  Files             92          92                 
  Lines          15855       15874         +19     
===================================================
+ Hits            9101        9109          +8     
- Misses          6147        6157         +10     
- Partials         607         608          +1     

Files with missing lines	Coverage Δ
monitor/census.go	66.29834% <69.23077%> (+0.00411%)	⬆️
server/broadcast.go	79.38689% <0.00000%> (-0.59181%)	⬇️

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Files with missing lines	Coverage Δ
monitor/census.go	66.29834% <69.23077%> (+0.00411%)	⬆️
server/broadcast.go	79.38689% <0.00000%> (-0.59181%)	⬇️

[mjh1]

I'll reopen this once we have a way of surfacing the capacity info from the Os