AMI430: Restore ramp rates of individual magnet axes after simultaneous ramp, for block_during_ramp is True or with call to wait_while_all_axes_ramping

[astafan8]

Apparently, it is confusing for users that the simultaneous ramp mode does not keep the ramp rate settings of the individual magnet axes intact. User's impression of the simultaneous ramp mode with the vector_ramp_rate parameter is that it sits on top of the individual axes and after the ramp is over, the individual magnet axes should still have their original individual ramp rates preserved.

In the implementation, restore_at_exit context managers of the ramp_rate parameters are used. The get exit-ed aka closed in the wait_while_all_axes_ramping, which means that not only users can run the simultanous ramps with block_during_ramp is True and the restoring will happen, but also the restoring will happen when users call wait_while_all_axes_ramping explicitly, even when block_during_ramp is set to False.

• test on real instrument
• test if after initiating a ramp, it is possible to change ramp rate on the fly; does instrument allow it or errors out, does it change the ramp rate or ignores it, etc

Credits to @JouriB for the idea and the help with testing, and @jenshnielsen for refining the implementation!

[codecov]

Codecov Report

Merging #3885 (840ddfe) into master (b3a7e38) will increase coverage by 0.27%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3885      +/-   ##
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+ Coverage   65.80%   66.07%   +0.27%     
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  Files         228      228              
  Lines       31129    31147      +18     
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+ Hits        20483    20579      +96     
+ Misses      10646    10568      -78     

[JouriB]

I tested the PR, it works as expected.

I also tested what happens when the ramp rate is changed during a ramp started with blocking. The ramp rate is in fact changed on the fly for the active ramp. So restoring the ramp rates for unblocked ramps does not seem to be possible.