[TASK] Add indexed search icon to plugin wizard

Adds a small icon to the plugin wizard to avoid the hacky 2 click access.
The icon is added to the tab "Plug-Ins".

Change-Id: Ib0b9705acaf69c0c49de660174c536caedda9292
Resolves: #34298
Releases: 6.3, 6.2
Reviewed-on: http://review.typo3.org/9221
Reviewed-by: Kay Strobach <typo3@kay-strobach.de>
Tested-by: Kay Strobach <typo3@kay-strobach.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>