License of catalog, metadata, etc.

**Describe the issue**
It is unclear what the license of the https://github.com/google/fonts/tree/main/catalog folder or `*/METADATA.pb` are, or if they are open-source licensed.

**To Reproduce**
Try to find a license for https://github.com/google/fonts/tree/main/catalog in the folder itself or the README license section https://github.com/google/fonts?tab=readme-ov-file#license

**Expected behavior**
I expect to find an Apache 2 license

**Additional context**
This Google Fonts GitHub Repo

Other folders are named by their license type and are easy to tell which license they have. I assume that `METADATA.pb` files are under the same license as their parent folder.

A comment from a maintainer about what license the `catalog` folder has and confirming the `METADATA.pb` file licenses would suffice for me.

Most of the other data and libraries are licensed under Apache 2 or MIT, and I think licensing the data that allows everyone to easily credit the font authors, even though not required, would be a nice thing to do.

EDIT: also
- https://github.com/google/fonts/tree/main/tags
- https://developers.google.com/fonts/docs/developer_api
- https://fonts.google.com/analytics

If I’m missing any other bits, feel free to add and clarify them here too.