[DataCatalog]: Revise methods and properties names for DataCatalog

[ElenaKhaustova]

Description

Users find the naming of public functions, such as add_feed_dict, unclear and confusing, making it difficult to understand their purpose.

We propose to:

1. Review and revise methods and properties names for DataCatalog to make them more descriptive and intuitive, clearly indicating their purpose and functionality.
2. Revisit our usage examples to make them more informative for users and replace io with catalog.

Relates to #3612

Context

• Some user feedback: "I didn't even know what add_feed_dict did until someone explained it to me."
• Currently, in some of our examples, we use io instead of catalog while the last is meant.

kedro/kedro/io/data_catalog.py

Line 681 in 27f5405

>>> io = DataCatalog()

[merelcht]

We could tackle this either by changing the current DataCatalog function names in the next breaking release, or by making sure that the public API for a new DataCatalog2 has better names. If we decide to build DataCatalog2 (obviously with a better name) alongside DataCatalog we don't actually need to do anything with this ticket, just keep in mind we name our methods clearly 🙂