Add definition for new TSConfig filetype .tsconfig to .editorconfig
file.

Change-Id: I3fd87abc8a8fe554692f61e548e37d4d02f74fa4
Resolves: #82879
Releases: master, 8.7
Reviewed-on: https://review.typo3.org/54493


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>