Add client side telemetry scanning/redaction

To help ensure that the data we send up is clean, all telemetry properties should be scanned for potential sensitive data and have that redacted. We currently are careful about what data we send up, but having such automatic scans in place at runtime help prevent any mistakes from causing a privacy incident.

The [Cred Scan](https://eng.ms/docs/microsoft-security/security/azure-security/cloudai-security-fundamentals-engineering/cred-bot-trinity) and [Privacy Guard](https://www.owiki.ms/wiki/Telemetry/Privacy/Privacy_Guard) tools can help with this.

Another option is to use what ADS telemetry does and implement a limited form of scanning here : https://github.com/microsoft/vscode-extension-telemetry/blob/v0.6.2/src/common/baseTelemetryReporter.ts#L255