[BUGFIX] RTE cannot run in IE 11+ with ExtJS 3.4.1

Solution: Configure a hook in frontend to add a meta tag just after
the head tag whenever rtehtmlarea is in use on the page and the user
agent is IE 11+. The meta tag instructs IE to emulate IE 10.

Resolves: #56192
Releases: 6.2
Change-Id: Icc81f14c107360a47a34403032e5fe7890f1d784
Reviewed-on: https://review.typo3.org/27776
Reviewed-by: Markus Klein
Reviewed-by: Wouter Wolters
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland