Implement /api/cloud-eval endpoint

[Anupya]

Description

• Add /api/cloud-eval endpoint in the new Analysis class.
• Added an explanation for PV and CP in the codebase because I had to look them up.
• Added a test.

After merge

Please check off /api/cloud-eval in #6.

Checklist

Checklist when adding a new endpoint

• Added new endpoint to the README.md
• Ensure that my endpoint name does not repeat the name of the client. Wrong: client.users.get_user(), Correct: client.users.get()
• Typed the returned JSON using TypedDicts in berserk/types/, example
• Tested GET endpoints not requiring authentification. Documentation, example
• Added the endpoint and your name to CHANGELOG.md in the To be released section (to be created if necessary) <-- leaving this to the maintainers to do

[kraktus]

thanks!