Shared database for evaluations of oellm-cli

Develop a database that allows to access all evaluations done by OELLM on our different clusters.

Once the database is available, it will be used to:

1. easily share evaluation accross the projects, right now scattered csv/json files are send around
2. check if an evaluation was already submitted to avoid repeating evaluation multiple times
3. update dynamically evaluation dashboard like this one which is currently static: https://huggingface.co/spaces/openeurollm/LLM-leaderboard

We should have:

1. automatic synchronisation of the DB
2. easy & fast way to access an evaluation (eg the json of a given model on MMLU)
3. easy & fast way to list evaluations for scientific analysis.

Reference/design doc:

• https://docs.google.com/document/d/1jofYjD_nfu4mypZQQRa0akyHUIyZ4brgBUePuQK-xwA/edit?tab=t.0#heading=h.unkgsjev4fxo
• https://docs.google.com/document/d/1Hza4Hxdz7zScTn4dGeHqauZr1LBcLONE2QwQnMsJTSQ/edit?tab=t.0#heading=h.gmxdx5bmgees