#30 add recipe default option to settings

[B-Hartmann]

This PR aims to close #30. It adds a new entry to the preferences to set the default recipe.
I updated the gui accordingly, populate the drowdown menu with the list of available recipes and make sure the value from the settings is loaded when the program starts.

What do you think?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 20.00000% with 8 lines in your changes missing coverage. Please review.

Project coverage is 56.54%. Comparing base (163c1cd) to head (b1e29ee).
Report is 18 commits behind head on main.

Files with missing lines	Patch %	Lines
mpl_data_cast/gui/preferences.py	11.11%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #31      +/-   ##
==========================================
- Coverage   56.85%   56.54%   -0.31%     
==========================================
  Files          19       19              
  Lines         897     1031     +134     
==========================================
+ Hits          510      583      +73     
- Misses        387      448      +61     

Flag	Coverage Δ
	56.54% <20.00%> (?)

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[B-Hartmann]

@paulmueller What do you think about this PR?

[paulmueller]

Thanks! Just a few minor changes 👍