[ENH] Create Instance: New widget

[VesnaT]

Issue

Implement a widget for creating an instance, based on input data.

Description of changes

• new widget
  

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #5033 into master will increase coverage by 0.07%.
The diff coverage is 96.76%.

@@            Coverage Diff             @@
##           master    #5033      +/-   ##
==========================================
+ Coverage   84.66%   84.73%   +0.07%     
==========================================
  Files         285      286       +1     
  Lines       59557    60042     +485     
==========================================
+ Hits        50423    50879     +456     
- Misses       9134     9163      +29     

[borondics]

Would it make sense to add the possibility of splitting the dataset according to categorical variables? Right now the category of the output instance can be selected by hand.

[markotoplak]

@borondics, what do you mean? Is what you say actually connected to this widget (Create instance)? This widget can only create a single output instance, thus I do not understand what you meant by splitting.

[borondics]

Yes, that way the widget would create one instance for each categorical class based on the class members.