[BUGFIX] Openid link is always shown

Show openid field and link only if EXT:openid is installed.
Additional an error in Login.js is fixed.

Resolves: #63072
Releases: master
Change-Id: I2055ae1b73387992af73f66d315ab52be9a633db
Reviewed-on: http://review.typo3.org/34368
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>