Add support for telemetry

[brikis98]

Many TG users are looking for a way to get telemetry data on what TG is doing under the hood so they can troubleshoot issues, improve performance bottlenecks, etc.

Proposal

• Update TG to emit telemetry data.
• Use OpenTelemetry as the format/tooling.
• This should be an opt-in feature you turn on with some sort of flag / env var.
• All data should be anonymous: no personal user IDs or anything like that should be included. That said, local file paths will be included.

Data to emit

We will need to do some thinking on what data to emit and when, but here's an initial list:

• What commands are running and in which folders.
  • Whether each command succeeded or failed.
  • How long each command took.
• What steps TG did internally (e.g., file system scanning, config parsing, auto-init, hook execution, etc) to process the command.
  • How long each step took.
  • Whether each step succeeded or failed.
• What TF modules and providers, and at which versions, were used.
  • How long it took to download them.
  • How big they are on disk.