[BUGFIX] Label show link of file info popup correctly

The info popup of a file shows a download button that does not
trigger a download. Instead the file is opened in a new tab.
This Patch changes the label to "Show" and the icon to the one
used in the filelist for the same action.

Change-Id: Ic1fe8f502d6c5fb38f8007c5394d7105e1daab30
Resolves: #70179
Releases: master
Reviewed-on: http://review.typo3.org/43632


Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>