Move codec tests into dedicated folder - #84

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/setup-java@v4, actions/upload-artifact@v4, astral-sh/setup-uv@v6. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

No file matched to [D:\a\zarr-java\zarr-java\**\*requirements*.txt,D:\a\zarr-java\zarr-java\**\*requirements*.in,D:\a\zarr-java\zarr-java\**\*constraints*.txt,D:\a\zarr-java\zarr-java\**\*constraints*.in,D:\a\zarr-java\zarr-java\**\pyproject.toml,D:\a\zarr-java\zarr-java\**\uv.lock,D:\a\zarr-java\zarr-java\**\*.py.lock]. The cache will never get invalidated. Make sure you have checked out the target repository and configured the cache-dependency-glob input correctly.