browse: Fix a couple of spotted issues in the UI

Ensure only source code is highlighted in content views

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Fix breadcrumb link for root directory in revision view.

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Rework "Download" button in content views to offer the same feature as the "Raw File" one except the content will be downloaded and saved to disk instead of rendering it in the browser.

Fixes #4834 (closed).

swh/web/browse/templates/includes/content-display.html

@@ -58,7 +58,7 @@ See top-level LICENSE file for more information
         let codeContainer = $('code');
         let content = codeContainer.text();
 
-        swh.webapp.highlightCode(true, 'code', !{{ iframe_mode|jsonify }});
+        swh.webapp.highlightCode(true, '.swh-content code', !{{ iframe_mode|jsonify }});
 
         function updateLanguage(language) {
           codeContainer.text(content);
@@ -71,7 +71,7 @@ See top-level LICENSE file for more information
           const newUrl = window.location.pathname + '?' + urlParams.toString() + window.location.hash;
           window.history.replaceState('', document.title, newUrl);
 
-          swh.webapp.highlightCode(true, 'code', !{{ iframe_mode|jsonify }});
+          swh.webapp.highlightCode(true, '.swh-content code', !{{ iframe_mode|jsonify }});
         }
 
       {% endif %}