Collect statistics about individual feature usage

[hyangah]

We want to collect the following stats to decide on prioritization

• Debug: usage of debug features (e.g. remote debugging, non-test debugging)
• Test: test explorer vs code lenses
• Gopls restart reasons: manual/update/crash counts
• 3rd party tools: gotests, impl, goplay

To support this, we will use the Go Telemetry, and report through the Gopls's telemetry proxy api.

[gopherbot]

Change https://go.dev/cl/549243 mentions this issue: vscgo: a little helper program

[gopherbot]

Change https://go.dev/cl/549244 mentions this issue: src/goInstallTools,goTelemetry: add TelemetryReporter