Add uniqueness check to "Create project" command (#5100)

* Add failing playwright test

* Make create generate a unique name if the given one collides

* Add a new consolidated getUniqueProjectName function with tests

* Use getUniqueProjectName

* Replace "New project" button text with "Create project"
cc @pierremtb

* Extend the e2e test to show the incrementing behavior
cc @lf94

e2e/playwright/fixtures/cmdBarFixture.ts

@@ -135,4 +135,20 @@ export class CmdBarFixture {
       await promptEditCommand.first().click()
     }
   }
+
+  get cmdSearchInput() {
+    return this.page.getByTestId('cmd-bar-search')
+  }
+
+  get argumentInput() {
+    return this.page.getByTestId('cmd-bar-arg-value')
+  }
+
+  get cmdOptions() {
+    return this.page.getByTestId('cmd-bar-option')
+  }
+
+  chooseCommand = async (commandName: string) => {
+    await this.cmdOptions.getByText(commandName).click()
+  }
 }