module.Manager.RunMigrations should probably call InitGenesis when new modules are added

[aaronc]

I was checking out module.Manager.RunMigrations to see what happens when new modules are added and created #8988.

When a module is added to a chain during an upgrade, we should probably be calling its InitGenesis method. Modules probably expect that InitGenesis was called at some point and may do some special initialization there even with empty genesis state. Either this should either happen automatically in RunMigrations (with an empty genesis state) or explicitly in the UpgradeHandler with possibly some initial state. What do you think @AmauryM @technicallyty ?

[amaury1093]

Calling InitGenesis with empty state iif fromVersion == 0 makes sense to me

If an app developer wants to override that, they can just explicitly set the module's fromVersion to the latest version in the upgrade handler, and call InitGenesis with their own custom genesis.

[aaronc]

Calling InitGenesis with empty state iif fromVersion == 0 makes sense to me

If an app developer wants to override that, they can just explicitly set the module's fromVersion to the latest version in the upgrade handler, and call InitGenesis with their own custom genesis.

Makes sense. I like that approach. Let's remember to document that.