Add support for running create-astro in cloned empty git repository

[HiDeoo]

Changes

When initializing a new Astro project, I realized that it is not currently possible to run create-astro in a cloned empty git repository. The current behavior is to check for truly empty directories. This could also be an issue for macOS users trying create a new Astro project in an existing directory containing a .DS_Store file.

I researched how other CLI tools handle this situation and found various solutions:

• Create React App maintains a list of files that should be safely ignored when checking for an empty directory.
• Create Next App uses an identical approach to Create React App with a slightly different list of files which add support for Yarn v2+.
• Vite only ignores .git directories.

This pull request adds support for this feature by using the same approach as Create React App & Create Next App and adding a list of file / directory names (or patterns) that can be safely ignored when checking for a valid project directory.

Testing

I added a test to check if create-astro is proceeding in a non-empty safe directory using a new nonempty-safe-dir fixture that contains an empty .gitignore file and module.iml file (both should be ignored respectively by an exact name match and a pattern match).

Docs

I couldn't find any mention of this specific behavior in the documentation so I'm not sure if any changes are needed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 1c65c13

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
create-astro	Patch

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[matthewp]

This looks great, thanks!