Added externalAppCardActionsForCEA APIs

[MengyiGong]

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Description

Added externalAppCardActionsForCEA APIs

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Main changes in the PR:

1. Added externalAppCardActionsForCEA APIs
2. Moved the common models used for both externalAppCardActionsForCEC and externalAppCardActions APIs into interface files.

Unit Tests added:

Unit tests are required for all changes. If no unit tests were added as part of this change, please explain why they aren't necessary.

End-to-end tests added:

Additional Requirements

Change file added:

Ensure the change file meets the formatting requirements.

Related PRs:

Remove this section if n/a

Next/remaining steps:

Add UI tests

[github-actions]

This pull request contains changes to the runtime.ts file. If you, as the author of this PR, have made changes to the Runtime interface please review RUNTIME.md to determine if a new runtime version is required. Please reply to this comment stating what changes, if any, were made to the runtime object and whether a new runtime version was required.

[MengyiGong]

Thanks @AE-MS for taking the time to review my PR and for leaving so many great suggestions. Updated the code to address them all.

[AE-MS]

Thanks for considering my input! With the updated code, I left just a few more comments/questions.

[TrevorJoelHarris]

Asked for some updates to documentation/comments

[AE-MS]

[AE-MS]