RTL: fix preferences layout (#9021)

app/javascript/styles/mastodon/rtl.scss

@@ -196,6 +196,10 @@ body.rtl {
     right: -2.14285714em;
   }
 
+  .admin-wrapper {
+    direction: rtl;
+  }
+
   .admin-wrapper .sidebar ul a i.fa,
   a.table-action-link i.fa {
     margin-right: 0;
@@ -214,11 +218,32 @@ body.rtl {
     right: 0;
   }
 
+  .simple_form .input.radio_buttons .radio {
+    left: auto;
+    right: 0;
+  }
+
+  .simple_form .input.radio_buttons .radio > label {
+    padding-right: 28px;
+    padding-left: 0;
+  }
+
   .simple_form .input-with-append .input input {
     padding-left: 142px;
     padding-right: 0;
   }
 
+  .simple_form .input.boolean label.checkbox {
+    left: auto;
+    right: 0;
+  }
+
+  .simple_form .input.boolean .label_input,
+  .simple_form .input.boolean .hint {
+    padding-left: 0;
+    padding-right: 28px;
+  }
+
   .simple_form .label_input__append {
     right: auto;
     left: 0;
@@ -230,6 +255,10 @@ body.rtl {
     }
   }
 
+  .simple_form select {
+    background: darken($ui-base-color, 10%) url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14.933 18.467' height='19.698' width='15.929'><path d='M3.467 14.967l-3.393-3.5H14.86l-3.392 3.5c-1.866 1.925-3.666 3.5-4 3.5-.335 0-2.135-1.575-4-3.5zm.266-11.234L7.467 0 11.2 3.733l3.733 3.734H0l3.733-3.734z' fill='#{hex-color(lighten($ui-base-color, 12%))}'/></svg>") no-repeat left 8px center / auto 16px;
+  }
+
   .table th,
   .table td {
     text-align: right;