Setting to collapse tab groups by default [closes #163, closes #372]

If a group hasn't been explicitly expanded or collapsed, the default can
now be changed so that such groups are always shown collapsed (until
explicitly expanded).

Thanks to @samca2 for the contribution!

src/model/options.ts

@@ -59,6 +59,12 @@ export const SYNC_DEF = {
     is: anEnum("unstashed", "all"),
   },
 
+  // How are new folders of tabs shown, expanded or collapsed?
+  show_new_folders: {
+    default: "expanded",
+    is: anEnum("expanded", "collapsed"),
+  },
+
   // How big should the spacing/fonts be?
   ui_metrics: {
     default: "normal",

src/options/index.vue

@@ -174,6 +174,12 @@
         <option value="unstashed">Unstashed tabs only</option>
         <option value="all">Stashed and unstashed tabs</option>
       </select>
+
+      <label for="show_new_folders">Show new tab groups:</label>
+      <select id="show_new_folders" v-model="sync.show_new_folders">
+        <option value="expanded">Expanded</option>
+        <option value="collapsed">Collapsed</option>
+      </select>
     </section>
 
     <hr />

src/stash-list/folder.vue

@@ -363,7 +363,11 @@ export default defineComponent({
 
     collapsed: {
       get(): boolean {
-        return !!this.metadata.value?.collapsed;
+        if (this.metadata.value === undefined) {
+          return the.model.options.sync.state.show_new_folders === "collapsed";
+        }
+
+        return !!this.metadata.value.collapsed;
       },
       set(collapsed: boolean) {
         the.model.bookmark_metadata.setCollapsed(this.metadata.key, collapsed);