Add a new version-update check telemetry event

[tmeasday]

Issue: N/A

What I did

Fire a telemetry event whenever version-update successfully runs. This makes it possible for us to tell if the version update logic is working correctly.

How to test

rm -rf node_modules/.cache/storybook

STORYBOOK_TELEMETRY_DEBUG=1 yst
# check for 'version-update' event

STORYBOOK_TELEMETRY_DEBUG=1 yst
# check for no 'version-update' event

If we had a smoke test we could also check that it gets emitted there; this will come later.

[shilman]

LGTM!