feat(invideoquiz-editor): add validation for required data

[djoseph-apphelix]

Description

• Add "Content not found" alert to the InVideoQuiz editor that displays when the parent unit is missing video or problem components
• Alert shows "No video found for this unit" and/or "No problem found for this unit" as applicable, with a bold "Content not found" heading
• Alert is dismissible via a "Dismiss" button and only appears after editor data has finished loading
• Add unit tests covering all alert scenarios (17 tests)

Screenshot

Impacted user roles:

This change is in the Studio (CMS) course authoring interface — specifically the InVideoQuiz XBlock editor. The impacted roles are:

• Course Staff — can edit course content in Studio
• Course Instructors/Admins — full course editing access in Studio
• Global Staff / Superusers — platform-wide Studio access

Supporting information

Jira ticket : TNL2-541

Testing instructions

• Open InVideoQuiz editor in a unit with no video components — verify "No video found for this unit" alert appears
• Open InVideoQuiz editor in a unit with no problem components — verify "No problem found for this unit" alert appears
• Open InVideoQuiz editor in a unit with neither — verify both messages appear in one alert
• Open InVideoQuiz editor in a unit with both video and problem components — verify no alert appears
• Click "Dismiss" — verify alert is hidden

[Copilot]

Pull request overview

This PR adds a "Content not found" alert to the InVideoQuizEditor that displays when the parent unit is missing video or problem components. The alert informs users about missing content with specific messages and can be dismissed via a button. The implementation includes comprehensive unit tests covering various alert scenarios.

Changes:

• Added internationalized alert messages for missing video/problem content
• Implemented conditional alert display logic based on loaded state and content availability
• Created 17 unit tests to cover alert display, dismissal, and edge cases

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/editors/containers/InVideoQuizEditor/messages.ts	Added four new i18n messages for alert title, content messages, and dismiss button
src/editors/containers/InVideoQuizEditor/index.jsx	Implemented alert UI with custom dismiss button, conditional rendering based on content availability
src/editors/containers/InVideoQuizEditor/index.test.jsx	Added comprehensive test suite with 17 tests covering alert scenarios and component behavior

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

Consider using variant="warning" instead of variant="danger" for this alert. Based on the codebase patterns, "danger" is typically reserved for errors and validation failures that prevent functionality, while "warning" is used for informational alerts. The "Content not found" scenario is informational - the editor still functions, but the user should be aware that video or problem components are missing from the unit. This follows the pattern used in EditorContainer.tsx and other files where warnings notify users about conditions that need attention but don't break functionality.

Suggested change

	<Alert variant="danger" dismissible onClose={() => setContentAlertDismissed(true)}>
	<Alert variant="warning" dismissible onClose={() => setContentAlertDismissed(true)}>