[ENH] partially validate local node JSON config

[surchs]

• Closes Raise warning when contents of local_nb_nodes.json aren't valid #31

Changes proposed in this pull request:

• define schema for input JSON that works with both single nodes and JSON array
• check that the input json fits the schema
• filter the parts of the JSON that fit the schema and discard the rest
• return the list of things that didn't fit the schema (no explicit test yet)

Checklist

• PR has an interpretable title with a prefix ([ENH], [FIX], [REF], [TST], [CI], [MNT], [INF], [MODEL], [DOC]) (see https://neurobagel.org/contributing/pull_requests for more info)
• PR links to GitHub issue with mention Closes #XXXX
• Tests pass
• Checks pass

For new features:

• Tests have been added

For bug fixes:

• There is at least one test that would fail under the original bug conditions.

[coveralls]

Pull Request Test Coverage Report for Build 7213419581

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• 77 of 77 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 98.731%

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Totals
Change from base Build 7091883393:	0.4%
Covered Lines:	389
Relevant Lines:	394

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💛 - Coveralls

[alyssadai]

Very cool use of jsonschema validation here @surchs!

Left a few 🍒 for your consideration; otherwise good to go!