Fix importing lit under rollup v3

The updated https://www.npmjs.com/package/@rollup/plugin-node-resolve
plugin now looks inside package.json and uses that as a reference.
It looks at the exports field.

See I31f91e807b78d435631f5a0bdd358e5c75b04f3e
and I9f400ebb021e64dffe8828be04844e840c71f0ec.

Change-Id: I06527b5a2e705f9f4e1097aa00e642939516a5c5
4 files changed