core: pass context to when clause

The commit passes the `context` (which is generally assigned to toolbar
items) in order to determine the when clause for toolbar items.

Signed-off-by: vince-fugnitto <vincent.fugnitto@ericsson.com>

packages/core/src/browser/shell/tab-bar-toolbar/tab-bar-toolbar.tsx

@@ -247,7 +247,7 @@ export class TabBarToolbar extends ReactWidget {
     }
 
     protected evaluateWhenClause(whenClause: string | undefined): boolean {
-        return whenClause ? this.contextKeyService.match(whenClause) : true;
+        return whenClause ? this.contextKeyService.match(whenClause, this.current?.node) : true;
     }
 
     protected executeCommand = (e: React.MouseEvent<HTMLElement>) => {