Validation: Exhaustive validation of runtime config (system and job)

Basic config validation has been included for 0.2.0.

The config system will eventually use proto files to describe the config schema, as config is shipped between components along with metadata. Full exhaustive validation will be added once that is implemented.

The scope is the config system and runtime configuration for both system and job configs; the issue also mentions proto files as the planned schema source. Start by checking whether the proto-based schema work exists and reading the current basic validation. Done means exhaustive validation is implemented for both config types after that dependency is available.

Written by the indexing model from the issue text.