feat: disable auto consent and add nuxt telemetry consent

[pi0]

Background: For sending telemetry events, we once consent users about sending events or not but since it wasn't possible to make a prompt and await on stdin in production and CI/CD environments, it was enabled by default on headless envs. (alternative was forcing on each project creation but at early days it was reported to be annoying even with a notice how to enable in CI)

With this change, we never send any events unless it is explicitly enabled per-machine or per-project.

Also a new cli command nuxt telemetry consent [-g] [dir] introduced so with a post creation hook in create-nuxt-app, we still have chance to opt in users but before first run.

Also I added consent field to events context so if later-on we change events policy, have a way to distinguish events. (clarify: currently if a policy change happens, we shall bump version to force prompt users again before sending events.)

Rolling-out strategy:

• All events with production env or ci: true tag will be wiped out from database to maximize privacy
• Older versions of @nuxt/telemetry npm package will be deprecated with a message to notify about implicit behavior and they should upgrade version
• New version is released as a semver-minor so essentially any new nuxt project will receive update without need to release another version of nuxt

closes #34