Add support for ensemble batch prediction intervals

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For time series models, see here and MAPIE

Tasks:

• [x] #57
• [x] #58

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cc @indymnv related to you tweet: https://twitter.com/lM_Navi/status/1609013982773272577?s=20&t=gXSTPwta1lBepjfyTe_R3w 😁

Not sure I'll get to this any time soon, but certainly interested. Related to #35 which @MojiFarmanbar is working on in the background.

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Closed by #57