Compartment mapper: validate compartment map JSON

[kriskowal]

Currently, the compartment mapper takes for granted that the compartment map is a valid instance of its purported schema. TypeScript calls us out on this, so there’s a forced cast in place in import-archive.js and a note to write a TS compliant validator to visit and assert the entire JSON shape.

#599 (comment)

[Tartuffo]

@kriskowal This does not have an area label that is covered by our weekly tech / planning meetings. Can you assign the proper label? We cover: agd, agoric-cosmos, amm, core economy, cosmic-swingset, endo, getrun, governance, installation-bundling, metering, run-protocol, staking, swingset, swingset-runner, token economy, wallet, zoe contract,