Add a .kiotaignore file so users can add which files Kiota shouldn't change

[maisarissi]

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

Based on the discussion in the #5977 (comment), we can introduce a new .ignore file so users can add patters and specific files Kiota shouldn't change when generating/regenerating.

This would allow folks to add project files to a client/plugin output directory and not get their files deleted/changed when regenerating.
This would also allow folks to manual edit any generated file and not get the content overridden by Kiota, like slightly changing a model or a request builder.

Describe the solution you'd like

Provide users with the ability to add a .ignore file so Kiota would use it when generating/regenerating and not change the content of that files.

When creating a client/plugin to an output folder that contains files already, Kiota should create the .ignore files with the whole content of the folder.

Additional context

This will be considered and prioritized based on community feedback and demand. So please, upvote if you would like that feature available.

[baywet]

To other team members reading this, I want to make something clear from the discussion: this is not committed to, we're simply trying to gather community feedback here.

Another aspect from our discussion is that while this is a common pattern, discoverability by the user will be a challenge, which is why we're not committing to doing this yet.