New examples

[blondered]

• Changed features processing example
• Added LightFM wrapper inference speed benchmark
• Added iALS with features quality benchmark

[codecov]

Codecov Report

Merging #60 (114c4b6) into main (9b3992e) will not change coverage.
Report is 14 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #60   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           45        45           
  Lines         2242      2282   +40     
=========================================
+ Hits          2242      2282   +40     

Files	Coverage Δ
rectools/compat.py	100.00% <100.00%> (ø)
rectools/metrics/classification.py	100.00% <100.00%> (ø)
rectools/metrics/diversity.py	100.00% <100.00%> (ø)
rectools/model_selection/__init__.py	100.00% <100.00%> (ø)
rectools/model_selection/last_n_split.py	100.00% <100.00%> (ø)
rectools/model_selection/random_split.py	100.00% <100.00%> (ø)
rectools/model_selection/splitter.py	100.00% <100.00%> (ø)
rectools/model_selection/time_split.py	100.00% <100.00%> (ø)
rectools/models/__init__.py	100.00% <100.00%> (ø)
rectools/models/dssm.py	100.00% <100.00%> (ø)
... and 7 more