feat: Add configuration for add_newline

[matchai]

Description

• Replace TableExt with a Config trait that extends toml::value::Table
• Add configuration for add_newline
add_newline is a root-level configuration value. When set to false, the initial newline before the prompt is removed.

What are your thoughts on making add_newline a root-level config value?

Motivation and Context

Closes #

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Screenshots (if appropriate):

How Has This Been Tested?

• I have tested using MacOS
• I have tested using Linux
• I have tested using Windows

Checklist:

• I have updated the documentation accordingly.
• I have updated the tests accordingly.