Modal does not contain Focus Cycling mechanism

[jeffredodd]

Description

In order to be WCAG 2.1 compliant, our Modal's with the role='dialog' must contain a mechanism to enforce focus cycling. A users focus must be contained within a modal to be compliant. See https://www.w3.org/TR/wai-aria-practices-1.1/#dialog_modal for more information.

Reproduction

1. Open a modal
2. Attempt to tab

Expected:

• Focus should remain within modal
• Focus should be redirected into modal when opened

Actual:

• Focus is not altered and left in last known state.

Note: This issue is seen in all 3 libraries
Fundamental-React: #345
Fundamental-NGX: SAP/fundamental-ngx#477
Fundamental-Vue: SAP/fundamental-vue#136