feat: Improved CLI file structuring

[ntkathole]

What this PR does / why we need it:

Breaking a large Click CLI file into multiple files improves maintainability and readability.

feast/
│── cli/
│   │── __init__.py
│   │── cli.py        # Entry point for CLI
│   │── group1.py      # Commands for group1
│   │── group2.py      # Commands for group2
|   |── command1.py  # Commands
│   └── cli_utils.py       # Shared Utility functions 
|   └── cli_options.py       # Shared Utility options

[ntkathole]

@jyejare ^

[franciscojavierarceo]

large PR, going to assume you tested this thoroughly. :)