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/workbench/services/insights/browser/insightsDialogView.ts

@@ -45,6 +45,7 @@ import { ITextResourcePropertiesService } from 'vs/editor/common/services/resour
 
 const labelDisplay = nls.localize("insights.item", "Item");
 const valueDisplay = nls.localize("insights.value", "Value");
+const iconClass = 'codicon';
 
 class InsightTableView<T> extends ViewletPanel {
 	private _table: Table<T>;
@@ -88,22 +89,22 @@ function stateFormatter(row: number, cell: number, value: any, columnDef: Slick.
 
 	// render icon if passed
 	if (resource.icon) {
-		icon.classList.add('icon');
+		icon.classList.add(iconClass);
 		icon.classList.add(resource.icon);
 	} else {
-		icon.classList.remove('icon');
+		icon.classList.remove(iconClass);
 	}
 
 	//render state badge if present
 	if (resource.stateColor) {
 		badgeContent.style.backgroundColor = resource.stateColor;
-		badgeContent.classList.remove('icon');
+		badgeContent.classList.remove(iconClass);
 	} else if (resource.stateIcon) {
 		badgeContent.style.backgroundColor = '';
-		badgeContent.classList.add('icon');
+		badgeContent.classList.add(iconClass);
 		badgeContent.classList.add(resource.stateIcon);
 	} else {
-		badgeContent.classList.remove('icon');
+		badgeContent.classList.remove(iconClass);
 		badgeContent.style.backgroundColor = '';
 	}