Add information about the analysers into the rsyncer api calls

[stephen-riggs]

This adds the length and status of any corresponding analyser queue to the information returned about an rsyncer.

I've ended up breaking the one-to-one relation between endpoints in server/api/instrument.py and instrument_server/api.py, but this seemed the easiest way to combine the rsyncer and analyser information.

[codecov]

Codecov Report

Attention: Patch coverage is 9.37500% with 29 lines in your changes missing coverage. Please review.

Project coverage is 28.71%. Comparing base (1f9d448) to head (94a845f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #571      +/-   ##
==========================================
- Coverage   28.75%   28.71%   -0.04%     
==========================================
  Files          80       80              
  Lines       10621    10645      +24     
  Branches     1417     1419       +2     
==========================================
+ Hits         3054     3057       +3     
- Misses       7465     7486      +21     
  Partials      102      102              

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