Fixes #9640.

This ended up being somewhat more fragile than originally anticipated.
For the `ajv` cli call to get the right versions, we needed to install
ajv as a dev dependency in the top-level package.json as well as at the
common/web/types level.

Ajv does not do all that well with ESM yet, either, so we use esbuild to
transform the compiled validators before building in typescript.

…-schemas