Issue #2402103 by nod_, bnjmnm, larowlan, flxa, anmolgoyal74, droplet, xjm, catch, gabesullice, lauriii, Dries, justafish: Add once.js to core

Issue #3174884 by raman.b, alexpott, lauriii, zrpnr, nod_: Update yarn dependencies for Drupal 9.1.0

Issue #3072906 by bnjmnm, zrpnr, Wim Leers, lauriii, catch, mpdonadio, xjm, rainbreaw, andrewmacpherson, mgifford, anevins, jhedstrom: Deprecate and remove jQuery UI datepicker

Issue #2981652 by ApacheEx, corbacho, drpal, dawehner, xjm, alexpott, lauriii: Format core JavaScript using recently add Prettier

Issue #2548195 by nod_, JohnAlbin, madhavvyas, sriharsha.uppuluri: Only use single quotes in JavaScript and update .eslintrc

Issue #1835016 by googletorp, nod_, KarenS, Sharique, Nitesh Sethia, mpdonadio: Polyfill date input type