Fix errors due to icon to codicon rename in VSCode (#7837)

Found numerous errors where icons weren't rendering correctly.
- Anything that's an action must have CSS using "codicon" not "icon"
since VSCode sets the "codicon" class automatically.
This affected Agent view in particular, but also:
  - acounts view
  - new tab view in dashboard
 - many more
- Anything referencing the common-icons.css icons needed updating.
This hid help tooltip text in FormContainer UI for example.
- Finally I tried to convert all references from icon -> codicon,
even when the CSS was technically correct. This was done
for maintainability reasons - from now on always add codicon.

Fixes #7827

src/sql/base/browser/ui/breadcrumb/media/breadcrumb.css

@@ -4,23 +4,23 @@
  *--------------------------------------------------------------------------------------------*/
 
 
-.vs .chevron-right.icon {
+.vs .chevron-right.codicon {
 	background-image: url("chevron_right.svg");
 }
 
-.vs-dark .chevron-right.icon,
-.hc-black .chevron-right.icon {
+.vs-dark .chevron-right.codicon,
+.hc-black .chevron-right.codicon {
 	background-image: url("chevron_right_inverse.svg");
 }
 
-breadcrumb .icon {
+breadcrumb .codicon {
 	background-size: 16px;
 	background-position: 50% 50%;
 	background-repeat: no-repeat;
 	padding: 8px;
 }
 
-breadcrumb .chevron-right.icon {
+breadcrumb .chevron-right.codicon {
 	background-size: 16px;
 	background-position: 50% 50%;
 	background-repeat: no-repeat;
@@ -29,4 +29,4 @@ breadcrumb .chevron-right.icon {
 
 breadcrumb .router-link {
 	cursor: pointer;
-}
+}