Module TYPO3/CMS/Core/DocumentService provides native JavaScript
functions to detect DOM ready-state returning a Promise<Document>.

`$(document).ready(() => {...});` can be replaced by
`documentService.ready().then(() => {...});`

Resolves: #91122
Releases: master
Change-Id: Id812f786430f1ced6265493dd0bae472b8144588
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64241


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>