Convert the config class to be a dataclass

[r0x0d]

The config class itself can also be a dataclass. We can convert it to make the code easier.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
command_line_assistant/config.py	85.71%	1 Missing ⚠️

Files with missing lines	Coverage Δ
command_line_assistant/config.py	76.00% <85.71%> (ø)