Make the NB_OPENNEURO_UPLOAD_API required

[rmanaem]

Put in a check at Vite config to not let the tool start when NB_OPENNEURO_UPLOAD_API is not set.
Example:
https://github.com/neurobagel/query-tool/blob/ecd504453b42d9291fe7b4b56627800a0cd73047/vite.config.ts#L8-L11

[github-actions]

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