Add list of lists component to web UI (#5811)

* Add list of lists component to web UI

* Add list adding

* Add list removing

* List editor modal

* Add API account search limited by following=true relation

* Rework list editor modal

* Remove mandatory pagination of GET /api/v1/lists/:id/accounts

* Adjust search input placeholder

* Fix rspec (#5890)

* i18n: (zh-CN) Add missing translations for #5811 (#5891)

* i18n: (zh-CN) yarn manage:translations -- zh-CN

* i18n: (zh-CN) Add missing translations for #5811

* Fix some issues

- Display loading/missing state for list timelines
- Order lists alphabetically in overview
- Fix async list editor reset
- Redirect to /lists after deleting unpinned list
- Redirect to / after pinning a list

* Remove dead list columns when a list is deleted or fetch returns 404

app/javascript/styles/mastodon/components.scss

@@ -2359,6 +2359,10 @@ button.icon-button.active i.fa-retweet {
   margin-left: 0;
 }
 
+.column-header__links .text-btn {
+  margin-right: 10px;
+}
+
 .column-header__button {
   background: lighten($ui-base-color, 4%);
   border: 0;
@@ -2398,6 +2402,14 @@ button.icon-button.active i.fa-retweet {
   &.animating {
     overflow-y: hidden;
   }
+
+  hr {
+    height: 0;
+    background: transparent;
+    border: 0;
+    border-top: 1px solid lighten($ui-base-color, 12%);
+    margin: 10px 0;
+  }
 }
 
 .column-header__collapsible-inner {
@@ -4440,3 +4452,86 @@ noscript {
     margin-bottom: 0;
   }
 }
+
+.column-inline-form {
+  padding: 7px 15px;
+  padding-right: 5px;
+  display: flex;
+  justify-content: flex-start;
+  align-items: center;
+  background: lighten($ui-base-color, 4%);
+
+  label {
+    flex: 1 1 auto;
+
+    input {
+      width: 100%;
+      margin-bottom: 6px;
+    }
+  }
+
+  .icon-button {
+    flex: 0 0 auto;
+    margin-left: 5px;
+  }
+}
+
+.drawer__backdrop {
+  cursor: pointer;
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  background: rgba($base-overlay-background, 0.5);
+}
+
+.list-editor {
+  background: $ui-base-color;
+  flex-direction: column;
+  border-radius: 8px;
+  box-shadow: 2px 4px 15px rgba($base-shadow-color, 0.4);
+  width: 40vh;
+  overflow: hidden;
+
+  h4 {
+    padding: 15px 0;
+    background: lighten($ui-base-color, 13%);
+    font-weight: 500;
+    font-size: 16px;
+    text-align: center;
+    border-radius: 8px 8px 0 0;
+  }
+
+  .drawer__pager {
+    height: 50vh;
+  }
+
+  .drawer__inner {
+    border-radius: 0 0 8px 8px;
+
+    &.backdrop {
+      width: calc(100% - 60px);
+      box-shadow: 2px 4px 15px rgba($base-shadow-color, 0.4);
+      border-radius: 0 0 0 8px;
+    }
+  }
+
+  &__accounts {
+    overflow-y: auto;
+  }
+
+  .account__display-name {
+    &:hover strong {
+      text-decoration: none;
+    }
+  }
+
+  .account__avatar {
+    cursor: default;
+  }
+
+  .search {
+    margin-bottom: 0;
+  }
+}