[FEATURE] Support defer attribute for JavaScript includes in TypoScript

When including JavaScript files in TypoScript, the HTML5 attribute 
`defer` is now supported.

Resolves: #80542
Releases: master
Change-Id: I81ff3968360585692ec586449f64856dc0541f93
Reviewed-on: https://review.typo3.org/54053


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>