[BUGFIX] trigger Backend.doLayout() on window resize

Resolves: #78464
Releases: master, 8.7
Change-Id: I8d861df1e047213a355d145e05a9131386c7439f
Reviewed-on: https://review.typo3.org/52991


Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Kott <benjamin.kott@outlook.com>