[VSCode] Fail to activate typespec extension when enable telemetry

[chunyu3]

The typespec extension activate failed when we set the telemetry key and enable the telemetry.

Root cause:
Typespec-vscode now use esbuild to build the library, and in that case, the TelemetryReporter is namespace, not constructor and cannot construct the instance. Then the process crash.

typespec/packages/typespec-vscode/src/telemetry/telemetry-client.ts

Line 47 in be2ca06

this._client = new (TelemetryReporter as any)(key);