Updates to the combined add-in & Teams tab sample

[Rick-Kirkham]

This PR updates the add-in part of the sample for a combined Teams tab and Office add-in.

1. The add-in now uses new Office.js APIs to automatically reflect changes in the user's chosen Office theme.
2. The latest versions of the office-addin-* utility libraries are used.
3. In the manifest, the deprecated "file" property is replaced with the "url" property.
4. The deprecated teams-fx CLI is replaced with the teamsapp-CLI (only in the add-in part of the sample)
5. The sample ReadMe is updated to account for items 1 - 4.

Copilot reviewed 3 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (3)

• samples/tab-add-in-combined/nodejs/add-in/package.json: Language not supported
• samples/tab-add-in-combined/nodejs/appManifest/manifest.json: Language not supported
• samples/tab-add-in-combined/nodejs/demo-manifest/manifest.json: Language not supported

[Pawank-MSFT]

Please clear commented doubt?

[Harikrishnan-MSFT]

Looks Good Approved !!!

[Pawank-MSFT]

looks correct, Approving!