telemetry(amazonq):Add metric telemetry for /doc

[KevinDing1]

Problem

• This commit introduces metric telemetry for the /doc, which will be triggered during the code generation process. The new telemetry will:
  1. Record successful and failure generation requests
  2. Track failed requests with specific error types
  3. Enable the setup of client monitoring alarms base on the metric data

Solution

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jpinkney-aws]

won't this always send an EndDocGeneration as success?

[KevinDing1]

If having error during doc generation, it will fall into the catch block and execute finally but skip the rest
followed the same pattern as /dev:

aws-toolkit-vscode/packages/core/src/amazonqFeatureDev/controllers/chat/controller.ts

Line 585 in 4b20c5a

await session.sendMetricDataTelemetry(MetricDataOperationName.EndCodeGeneration, MetricDataResult.Success)