[WebIDE] Inform users when multi domain architecture is disabled

Problem to solve

When the multi domain architecture is disabled, there are several features that don't work in the Web IDE:

1. Web views are disabled.
2. The Extension Marketplace is disabled.

The multi domain architecture is disabled when the cdn.web-ide.gitlab-static.net assets host is unreachable or the Gitlab instance doesn't have HTTPS enabled. In this context, the Web IDE doesn't explain the user why these features are disabled.

Proposed solution

Display a warning message in the Web IDE that communicates to the user that some features in the Web IDE were disabled for security reasons.

Acceptance criteria

• Display the following warning message when the Web IDE starts and the crossOriginExtensionHost property is false: "Web views and the Extension Marketplace were disabled for security reasons. The Web IDE requires HTTPs and an external extension host to isolate 3rd-party code."
• The information message is dismissible.
• Persist the dismiss decision.
• Request technical writing review to revisit the UI text.