refactor(orm)!: support core genesis

[aaronc]

Description

This refactors the ORM's JSON code to support the core API genesis. Module's using the ORM would just need to embed to do something like this:

type Keeper struct {
  appmodule.HasGenesis
  ...
}

func NewKeeper(db ormdb.ModuleDB) *Keeper {
  ...
  return &Keeper{HasGenesis: db.AppModuleGenesis(), ...}
}

This also fixes a broken test introduced in #14796. Maybe something is broken in CI??

---

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[aaronc]

Or maybe simply:

Suggested change

	AppModuleGenesis() appmodule.HasGenesis
	Genesis() appmodule.HasGenesis

[aaronc]

Renamed to GenesisHandler. That feels a bit better

[facundomedica]

LGTM, we might need a changelog entry

[aaronc]

Added a CHANGELOG.md. Going to enable auto-merge unless anyone has any objections