Guard convertToSingleHost against deeply nested JSON config files

[ayush-meghwani-28]

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Change Description:

convertToSingleHost.js reads launch.json / package.json / tasks.json, modifies them, and writes them back with JSON.stringify(content, null, 2). Node's JSON.stringify is recursive, so a config file containing extremely deeply nested JSON causes an opaque "RangeError: Maximum call stack size exceeded" (JSON.parse itself succeeds since it is iterative).

This PR wraps the write-back serialization in a small helper that catches that RangeError and rethrows a clear, actionable message naming the affected file, instead of an opaque stack overflow. Normal template content is unaffected.

1. Do these changes impact any npm scripts commands (in package.json)? (e.g., running 'npm run start')
   If Yes, briefly describe what is impacted.
   => No

2. Do these changes impact VS Code debugging options (launch.json)?
   If Yes, briefly describe what is impacted.
   => No

3. Do these changes impact template output? (e.g., add/remove file, update file location, update file contents)
   If Yes, briefly describe what is impacted.
   => No

4. Do these changes impact documentation? (e.g., a tutorial on https://docs.microsoft.com/en-us/office/dev/add-ins/overview/office-add-ins)
   If Yes, briefly describe what is impacted.
   => No

If you answered yes to any of these please do the following:
> Include 'Rick-Kirkham' in the review
> Make sure the README file is correct

Validation/testing performed:

• Ran convertToSingleHost.js against a project whose .vscode/launch.json contained a deeply nested value. Before: crashed with "RangeError: Maximum call stack size exceeded". After: fails with a clear message: 'Unable to update ".vscode/launch.json": its JSON content is too deeply nested.'
• Verified normal template content converts exactly as before (unchanged output).
• node --check passes on the modified script

[ayush-meghwani-28]

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[millerds]

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[millerds]

Note that this only fixes this one template repo. There are several others (including excel-custom-functions-js, excel-custom-functions-shared*, and office-addin-taskpane* respos).