55 scan tasks should be stopped cleanly when process stopped

[evvaaaa]

Closes #55

[codecov]

Codecov Report

Attention: Patch coverage is 86.95652% with 3 lines in your changes missing coverage. Please review.

Project coverage is 82.54%. Comparing base (bdab4fa) to head (b0c21ee).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/fastcs/backend.py	86.95%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
- Coverage   82.75%   82.54%   -0.22%     
==========================================
  Files          23       23              
  Lines         928      934       +6     
==========================================
+ Hits          768      771       +3     
- Misses        160      163       +3     

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[jsouter]

Works okay against fastcs-eiger

[jsouter]

sorry I was hasty there, the scan tasks seem to take about ~5-10s to start now compared to before where it was immediate

[evvaaaa]

@jsouter
Ah okay I'll take late lunch break and make a new PR. Is this scan tasks in tests, or on the real eiger?

[jsouter]

Running python -m fastcs_eiger ioc <PV_PREFIX> against the tickit sim, all I did was just add a print message to the EigerController.update to see how long it takes to start spitting it out.