[TASK] Remove *.js.map from repository

This patch removes *.js.map files from the repository and adds a new
rule to the .gitignore file.

Resolves: #78407
Releases: master
Change-Id: I227dc1748a0b53910d7fc2050ccf92bfd555d4ec
Reviewed-on: https://review.typo3.org/50348


Reviewed-by: Patricia Tiedemann <pixelaeffchen@googlemail.com>
Tested-by: Patricia Tiedemann <pixelaeffchen@googlemail.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>