feature request: CNA add ".github" directory to allowed list when doing an empty check

[chrisweb]

Goals

1. the goal is to be able to use CNA even when there is already a .github directory present

Non-Goals

1. save the world

Background

a use case is vibe coding, when using github copilot you can create reusable prompt files that you put into .github/prompts, those *.prompt.md files can then get used in github copilot chat to vibe code using the agent mode

I have a prompt file called cna.prompt.md, I used it as first step to create a new blank next.js project, a reproduction repository is here: https://github.com/chrisweb/reproduction_create-next-app_empty_directory

Proposal

I propose to add .github to the CNA "isFolderEmpty" allow list, I already prepared a PR #79551 (when I did not yet know that you are supposed to first start a discussion, sorry, I instead had opened an issue: #79550)