[FEATURE] Add possibility to write tests in TypeScript

Adjust grunt and tsconfig to allow writing unit tests
in TypeScript. Test example is included.

Additionally configuration was adjusted to allow running
grunt tasks on windows and linux.

Change-Id: Ibeb0c501242afbbe796726a85329d14257acfd1c
Resolves: #81601
Releases: master
Reviewed-on: https://review.typo3.org/53248


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>