Support commented out config lines

### Is your feature request related to a problem? Please describe.

Enhance `Igniter.Project.configure/6` to allow passing an option which generates the config, but as a commented line.

This is useful for cases were a config line wants to be added as a hint.

### Describe the solution you'd like

There is an exisiting implementation for this here: https://github.com/mimiquate/tower_email/pull/63

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start by reading Igniter.Project.configure/6 and the existing implementation in mimiquate/tower_email pull request 63. The work is done when an option allows generated config lines to appear as comments, preserving their usefulness as hints.

Written by the indexing model from the issue text.