Pretty printing: DataCatalog.__repr__

[ElenaKhaustova]

Description

Parent ticket: #3913
Blocked by: #3980

Implement __repr__ for DataCatalog for better catalog representation and printing.

Context

#3913 (comment)
#1721

Possible Implementation

• Implement AbstractDataset pretty printing: Pretty printing: AbstractDataset.__repr__ #3980
• implement __repr__ for DataCatalog based on dataset's __repr__

[ElenaKhaustova]

Similarly to printing datasets two approaches were implemented:

• both approaches implement __repr__() method for _FrozenDatasets and DataCatalog based on the implementation __repr__() for dataset with aadded top-level keys - datastets' names. Since __str__ method is not implemented __repr__() is called when converting object to string, so we have the same results when print(obj), obj.
• Pretty printing catalog #3990

• Pretty printing catalog with indentation #3992
  
  

[ElenaKhaustova]

The non-indented version was preferred to the indented, closing #3992

[ElenaKhaustova]

Solved in #3990