Add telemetry for adapterPath config usage (#92228)
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## What?
Adds telemetry tracking for when the `adapterPath` config option is used
in Next.js.
## Why?
As mentioned in the Slack discussion, telemetry for adapter usage was
missing. This helps track adoption of the adapter feature.
## How?
- Added `adapterPath` field to the `EventCliSessionStarted` type in
`telemetry/events/version.ts`
- The field is automatically populated from `nextConfig.adapterPath`
when CLI sessions start
- This covers both `next dev` and `next build` commands
The telemetry emits a CLI session event with `"adapterPath": true` when
the config option is set, and `"adapterPath": false` when it's not.
## Testing
Updated the test in `test/integration/telemetry/test/config.test.ts` to:
1. Create a config with `adapterPath` set
2. Run a build with telemetry debug enabled
3. Verify the CLI session telemetry includes `"adapterPath": true`
The test passes locally.
