UX polish and refactor

- Visual polish for the settings page, keyboard shortcuts page, and outdenting tooltip
- Tweak copy throughout the app to make it a little simpler
- Add the ability to fetch the name of the meta key (i.e. Cmd or Ctrl) so it can be displayed to the user
- Make it possible to Cancel out of editing a keyboard shortcut, rather than the only option being to Save

resources/css/table.css

@@ -9,10 +9,6 @@ table {
     margin: 1rem 0;
 }
 
-tr {
-    border-bottom: 1px solid var(--ls-border-color);
-}
-
 th {
     font-size: 14px;
     font-weight: 400;
@@ -22,7 +18,6 @@ th {
 }
 
 td {
-    border-bottom: 1px solid var(--ls-border-color);
     padding: 6px 8px;
     text-align: left;
 }