WIP: Load datatables with an ES import

[mwouts]

In this PR we switch to a pure ES import of datatables, cf. DataTables/DataTablesSrc#199

Closes #51

What remains:

• Test itables in Jupyter Notebook
• Test itables in Jupyter Lab
• Load jQuery from a more classical CDN than https://ems.sh
• Load DataTables from a safer CDN than https://nightly.datatables.net
• Use SRI on both imports (maybe start at https://stackoverflow.com/questions/52636690/subresource-integrity-for-es6-import-or-worker)

[codecov-commenter]

Codecov Report

Merging #60 (6415f30) into main (f03c276) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #60   +/-   ##
=======================================
  Coverage   96.65%   96.65%           
=======================================
  Files          14       14           
  Lines         329      329           
=======================================
  Hits          318      318           
  Misses         11       11           

Impacted Files	Coverage Δ
itables/javascript.py	96.58% <100.00%> (ø)

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[mwouts]

Will do #76 instead