fix: Prevent Cleared event being raised when there aren't any tokens

[nickrandolph]

GitHub Issue (If applicable): #745

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

ITokenCache.Cleared event being raised even when there's no tokens in the cache

What is the new behavior?

Cleared event is only raised when there are existing tokens in the cache that are being cleared

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Docs have been added/updated which fit documentation template. (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Wasm UI Tests are not showing unexpected any differences. Validate PR Screenshots Compare Test Run results.
• Contains NO breaking changes
• Updated the Release Notes
• Associated with an issue (GitHub or internal)

Other information

Internal Issue (If applicable):