merge graphcast

[yairchn]

Earth-2 MIP Pull Request

Taking the branch in #134 and merging recent changes from main. Solving some conflict and applying noqa to asserts. Renaming tests --> test and combining the files from the two branches.

Description

Checklist

• [x] I am familiar with the Contributing Guidelines.
• [x] New or existing tests cover these changes.
• [x] The documentation is up to date with these changes.
• [x] The CHANGELOG.md is up to date with these changes.
• [x] An issue is linked to this pull request.

Dependencies

[NickGeneva]

/blossom-ci

[NickGeneva]

Moved here: https://github.com/NVIDIA/earth2mip/pull/145

Closing.