Prevent unchecked default lists from being visually collapsed

Related issue:
- https://github.com/gorhill/uBlock/issues/2303

src/css/3p-filters.css

@@ -57,7 +57,7 @@ body.hideUnused #listsOfBlockedHostsPrompt::before,
     margin-inline-start: 0.6em;
     -webkit-margin-start: 0.6em;
     }
-.groupEntry:not([data-groupkey="user"]) .listEntry.unused {
+.groupEntry:not([data-groupkey="user"]) .listEntry:not(.isDefault).unused {
     display: none;
     }
 .listEntry > * {

src/js/3p-filters.js

@@ -120,6 +120,7 @@ const renderFilterLists = function(soft) {
             } else {
                 li.classList.remove('mustread');
             }
+            li.classList.toggle('isDefault', entry.isDefault === true);
             li.classList.toggle('unused', hideUnused && !on);
         }
         // https://github.com/gorhill/uBlock/issues/1429

src/js/assets.js

@@ -873,6 +873,15 @@ api.metadata = async function() {
     for ( const assetKey in assetDict ) {
         const assetEntry = assetDict[assetKey];
         const cacheEntry = cacheDict[assetKey];
+        if (
+            assetEntry.content === 'filters' &&
+            assetEntry.external !== true
+        ) {
+            assetEntry.isDefault =
+                assetEntry.off === undefined ||
+                assetEntry.off === true &&
+                    µBlock.listMatchesEnvironment(assetEntry);
+        }
         if ( cacheEntry ) {
             assetEntry.cached = true;
             assetEntry.writeTime = cacheEntry.writeTime;