[BUGFIX] fix refresh icon: use the TYPO3 Icon API instead of plain html

Resources/Private/Partials/SelectExtensionAndLanguageFile.html

 {namespace lfe=SGalinski\Lfeditor\ViewHelpers}
+{namespace core=TYPO3\CMS\Core\ViewHelpers}
 
 <h2 class="uppercase">
 	<f:translate key="select.langfile" />
@@ -35,8 +36,8 @@
 
 <f:form id="refreshLanguageFileListForm" action="refreshLanguageFileList" class="tx-lfeditor-inline-block-form">
 	<span class="tx-lfeditor-buttons">
-		<button class="tx-lfeditor-buttons-refresh">
-			<span title="{f:translate(key:'button.refreshLanguageFileList.title')}" class="t3-icon t3-icon-actions t3-icon-system-refresh"></span>
+		<button class="tx-lfeditor-buttons-refresh" title="{f:translate(key:'button.refreshLanguageFileList.title')}">
+			<core:icon identifier="actions-system-refresh" size="small" />
 		</button>
 	</span>
 </f:form>