Allow TokenItemAdding to invoke even if data is not string

[kaismic]

Fixes #529

PR Type

What kind of change does this PR introduce?

Other: Feature added

What is the current behavior?

See issue #5006

What is the new behavior?

See issue #5006

PR Checklist

Please check if your PR fulfills the following requirements:

• [o] Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• [o] Based off latest main branch of toolkit
• [o] Tested code with current supported SDKs
• [o] Contains NO breaking changes

Other information

[kaismic]

@dotnet-policy-service agree