Add support for conversion to Google dataset search metadata

[satra]

This adds a function to convert a dandiset metadata schema to Google dataset search form.

However to embed the metadata on a webpage a few additional steps need to happen:

• expand the metadata using jsonld expand
• compact the metadata using a new context: {"@context": "http://schema.org/"}

this would either require adding pyld (which works but hasn't seen an update in a while), or doing it in javascript.

[codecov]

Codecov Report

Attention: Patch coverage is 95.91837% with 6 lines in your changes missing coverage. Please review.

Project coverage is 97.74%. Comparing base (782c421) to head (fdf13e1).

Files with missing lines	Patch %	Lines
dandischema/utils.py	93.02%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #293      +/-   ##
==========================================
- Coverage   97.88%   97.74%   -0.14%     
==========================================
  Files          16       17       +1     
  Lines        1983     2129     +146     
==========================================
+ Hits         1941     2081     +140     
- Misses         42       48       +6     

Flag	Coverage Δ
unittests	97.74% <95.91%> (-0.14%)	⬇️

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[satra]

i'm going to close this in favor of simply using datacite for now. i'll send a PR to dandiarchive for that.

curl -LH "Accept: application/ld+json" https://doi.org/10.48324/dandi.000617/0.250312.0130

what they generate doesn't pass the validator fully, but for our purposes it's a better route at the moment.

[satra]

PR submitted: dandi/dandi-archive#2212