[FIX] Linear Projection: Fix LDA

[lanzagar]

Issue

Fixes #5359

Description of changes

I thought about removing the overriden effective_data (which also fixes LDA), but then saw that it was done based on a talk between @janezd and @VesnaT (#4846 (comment)) who must have had a good reason for it.
So I just added the class to effective_data, but @janezd or @VesnaT should confirm that that makes sense.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #5828 (1bf5e7e) into master (3516fc3) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5828      +/-   ##
==========================================
+ Coverage   86.20%   86.21%   +0.01%     
==========================================
  Files         316      316              
  Lines       66618    66630      +12     
==========================================
+ Hits        57426    57444      +18     
+ Misses       9192     9186       -6     

[VesnaT]

Adding the class to effective_data makes sense, but the _invalidated/_domain_invalidated flags should be changed accordingly.

The following example does not work correctly:
1 . File (Iris) -> Select Columns (Reset) -> Linear Projection (LDA)
2. In the Select Columns move Iris to Ignored -> In Linear Projection the Circular Placement is selected and LDA is disable but the plot is not changed.
3. In the Select Columns move Iris back to Target -> In Linear Projection the Circular Placement in selected and LDA enabled but the plot is still not changed.

[VesnaT]

I just realised this wont work because class variable is duplicated when selected in effective variables.