Easier debugging of hydration mismatch

[tpluscode]

Should this be an RFC?

• [x] This is not a substantial change

Which package is this a feature request for?

SSR (@lit-labs/ssr)

Description

When a hydration mismatch happens, it would be nice to have a more meaningful error in the console. It should at least mention what is the DOM element where the issue occurred

Alternatives and Workarounds

Can't think of any right now