Add support for AimTTi QL355TP

[AdamVerner]

Hi,
I have added AimTTi QL355TP power supply.

I also moved the lookup table for other power supplies in case someone wants to easily add his device.

[astafan8]

@AdamVerner thank you!

would you mind adding a 5021.improved_driver newsfragment file as explained below:

Please create a file in the format number.categoryofcontribution in docs\changes\newsfragments. Here the number should be the number of the pull request. To get the number of the pull request one must first open the pull request and then subsequently update the number. The category of contribution should be one of breaking, new, improved, new_driver improved_driver, underthehood. The file should contain a small description of what is changed.

( this is mentioned in our contribution docs https://qcodes.github.io/Qcodes/community/contributing.html#pull-requests )

[codecov]

Codecov Report

Merging #5021 (f8caf8c) into master (eaa05d2) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5021   +/-   ##
=======================================
  Coverage   67.22%   67.22%           
=======================================
  Files         356      357    +1     
  Lines       29730    29733    +3     
=======================================
+ Hits        19985    19988    +3     
  Misses       9745     9745           

[jenshnielsen]

@AdamVerner we have standadized on having an explicit class for each driver and having these exposed at the top level. Looking at https://github.com/QCoDeS/Qcodes/tree/master/qcodes/instrument_drivers/AimTTi and https://github.com/QCoDeS/Qcodes/blob/master/qcodes/instrument_drivers/AimTTi/__init__.py could you add a class for the new driver to the init file similar to the other drivers

[AdamVerner]

Thanks i have added those changes. I also rebased back onto master so it's easier to merge.