[BUGFIX] Use empty alt text for EM extension icons

For images that cannot be loaded (e.g., when the extension is outside
the document root), the extension name will be printed twice, which
looks ugly and also breaks the layout.

As the extension icon is purely decorative, the alt attribute should
be an empty string.

Resolves: #91031
Releases: master, 9.5
Change-Id: I71be7978cc3245f127d864586dd5d54c1a6aae10
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64167


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: Christian Eßl <indy.essl@gmail.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Christian Eßl <indy.essl@gmail.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>

typo3/sysext/extensionmanager/Resources/Private/Templates/Distribution/Show.html

@@ -4,7 +4,7 @@
 
     <div class="distribution-detail">
         <div class="distribution-detail-previewpane">
-            <em:distributionImage extensionkey="{extension.extensionKey}" alt="{extension.title}" height="225" width="300" />
+            <em:distributionImage extensionkey="{extension.extensionKey}" alt="" height="225" width="300" />
         </div>
         <div class="distribution-detail-body">
             <div class="distribution-detail-header">

typo3/sysext/extensionmanager/Resources/Private/Templates/List/Index.html

@@ -96,7 +96,7 @@
                     </td>
                     <td>
                         <f:if condition="{extension.icon}">
-                            <img class="extension-icon" src="{extension.icon}" alt="{extension.title}" />
+                            <img class="extension-icon" src="{extension.icon}" alt="" />
                         </f:if>
                         <span title="{extension.description}">{extension.title}</span>
                     </td>