[4.4] system test for com_installer (#41483)

* system test for com_installer

* cs

Author: alikon

tests/System/integration/api/com_installer/Request.cy.js

@@ -0,0 +1,8 @@
+describe('Test that installer API endpoint', () => {
+  it('can deliver a list of extensions', () => {
+    cy.api_get('/extensions')
+      .then((response) => cy.wrap(response).its('body').its('data.0').its('attributes')
+        .its('name')
+        .should('include', 'Action Log - Joomla'));
+  });
+});