[TASK] t3skin: Base login screen input on Bootstrap

Inherit input field styles from bootstrap for login screen.

Resolves: #61557
Releases: master
Change-Id: I5036841fe2c5c10f4d62dfc40534039d6f5dddd9
Reviewed-on: http://review.typo3.org/32740
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>