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/errorMessage/browser/errorMessageDialog.ts

@@ -107,13 +107,13 @@ export class ErrorMessageDialog extends Modal {
 	private updateIconTitle(): void {
 		switch (this._severity) {
 			case Severity.Error:
-				this.titleIconClassName = 'sql icon error';
+				this.titleIconClassName = 'sql codicon error';
 				break;
 			case Severity.Warning:
-				this.titleIconClassName = 'sql icon warning';
+				this.titleIconClassName = 'sql codicon warning';
 				break;
 			case Severity.Info:
-				this.titleIconClassName = 'sql icon info';
+				this.titleIconClassName = 'sql codicon info';
 				break;
 		}
 	}

src/sql/workbench/services/errorMessage/browser/media/errorMessageDialog.css

@@ -9,7 +9,7 @@
 	height: 200px;
 }
 
-.error-dialog .icon.error, .error-dialog .icon.warning , .error-dialog .icon.info {
+.error-dialog .codicon.error, .error-dialog .codicon.warning , .error-dialog .codicon.info {
 	width: 20px;
 	height: 20px;
 	float: left;
@@ -22,6 +22,6 @@
 	user-select: text;
 }
 
-.modal .footer-button a.monaco-button.monaco-text-button.icon.scriptToClipboard {
+.modal .footer-button a.monaco-button.monaco-text-button.codicon.scriptToClipboard {
 	width: 120px;
-}
+}