Fixes #7599: Improved print styles for a few key components

* Updates `.table` to always enforce a solid white background
* Update button groups and dropdowns to always use black carets
* Add a 1px solid black border to labels (in the future we should add a
border to these perhaps for better printing)

docs/assets/css/bootstrap.css

@@ -266,6 +266,17 @@ table {
   .navbar {
     display: none;
   }
+  .table td,
+  .table th {
+    background-color: #fff !important;
+  }
+  .btn > .caret,
+  .dropup > .btn > .caret {
+    border-top-color: #000 !important;
+  }
+  .label {
+    border: 1px solid #000;
+  }
 }
 
 * {

less/print.less

@@ -71,4 +71,15 @@
   .navbar {
     display: none;
   }
+  .table td,
+  .table th {
+    background-color: #fff !important;
+  }
+  .btn > .caret,
+  .dropup > .btn > .caret {
+    border-top-color: #000 !important;
+  }
+  .label {
+    border: 1px solid #000;
+  }
 }