[TASK] Add latest changes to ChangeLog.txt

In preparation of the Alpha2 release of TYPO3 CMS 6.2 the latest
changes in extbase were added to the ChangeLog file.

Releases: 6.2
Resolves: #49894
Change-Id: I3ca728147dc4eed7c27dd5f2039336d1d2b52472
Reviewed-on: https://review.typo3.org/22202
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring