[Outreachy Task Submission] No Focus Trap On The Onboarding Modal.

[MugoBrian]

Describe the bug
On the onboarding modal, there is currently no focus trap implemented.

Where was the bug observed
In the onboarding modal in the web platform.

To Reproduce
Steps to reproduce the behavior:

1. Navigate to the Ushahidi platform.
2. Access the browser's developer tools console and clear or modify the value of "USH_is_onboarding_done" to true in the local storage. Afterward, refresh the page.
3. Utilize the tab key on your keyboard to navigate through the elements on the page.

Expected behavior
The tab focus indicator currently shifts to elements outside the modal without closing it. Ideally, it should cycle through the modal's focusable elements and return to the first one within the modal upon reaching the last one.

Is there a workaround? What is it.
The workaround involves incorporating a cdkTrapFocus directive within the onboarding modal component.

Screencast
Focus Trap Issue In Onboarding Modal.webm

Desktop Hardware Details (please complete the following information):
Browser: Chrome & Firefox