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/parts/tasks/browser/tasksRenderer.ts

@@ -56,7 +56,7 @@ export class TaskHistoryRenderer implements IRenderer {
 	public renderTemplate(tree: ITree, templateId: string, container: HTMLElement): any {
 		const taskTemplate: ITaskHistoryTemplateData = Object.create(null);
 		taskTemplate.root = dom.append(container, $('.task-group'));
-		taskTemplate.icon = dom.append(taskTemplate.root, $('.icon.task-icon'));
+		taskTemplate.icon = dom.append(taskTemplate.root, $('.codicon.task-icon'));
 		taskTemplate.label = dom.append(taskTemplate.root, $('.label'));
 		taskTemplate.description = dom.append(taskTemplate.root, $('.description'));
 		taskTemplate.time = dom.append(taskTemplate.root, $('.time'));