Expose the Sentry Error Id on the error page

[wesbos]

Would be funny to make our error page say something like:

Oopsie Dasiy. We had an error.

Don't worry, we boxed it up and gave it a name. Your error is little baby 4sd4sdf234k2l3j4 and we're rushing to the tend to it right now.

THEN if we can make the syntax site errors public and link to it? is that possible?

I did some early look into it and the sentry captureException API returns the ID. The Sveltekit lib doesn't return the ID, so we would either need to change that, or just re-implment the handlerError function here: https://github.com/getsentry/sentry-javascript/blob/develop/packages/sveltekit/src/server/handleError.ts#L24

cc @benvinegar for ideas on this