[TASK] Deprecate JavaScriptEncoder class

The JavaScriptEncoder class was superseded with GeneralUtility::quoteJSvalue() in TYPO3 6.2
and is not used anymore. It is marked as deprecated.

Resolves: #85120
Releases: master
Change-Id: I13cb97e3ff6bb23d937a5193d392f92eb759ba9d
Reviewed-on: https://review.typo3.org/57093


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>