This replaces the JavaScript interpreter used by the console with goja,
which is actively maintained and a lot faster than otto. Clef still uses otto
and eth/tracers still uses duktape, so we are currently dependent on three
different JS interpreters. We're looking to replace the remaining uses of otto
soon though.
* les: move the checkpoint oracle into its own package
It's first step of refactor LES package. LES package
basically can be divided into LES client and LES server.
However both sides will use checkpoint package for
status retrieval and verification. So this PR moves
checkpoint oracle into a separate package
* les: address comments
