Include global level obs repo directory

[TeaganKing]

Description of changes:

It would be beneficial to only specify the global obs repo once rather than in every description of particular components' notebook parameters. Then, each component config file section can specify the latter part of the path to their observations.

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• Have you followed the guidelines in our Contributor's Guide?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
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  • Yes, and this work seems to pass tests, although some uxarray issues are cropping up with Meg's notebook...

[TeaganKing]

Hi @dabail10 , would it be alright with you if we remove these hard coded parameters from the cell, and instead make it clear that they come from the config file by just providing empty strings? @mnlevy1981 said that you were perhaps wanting to run this notebook outside of CUPiD as well, but I'm thinking you probably won't need these particular defaults anyways, and they may add more confusion.