need to set_keys in pallet_session in running chain

[farazahmadvaival]

I am running a solo chain with Genesis authorities set up for AURA and GRANPA. Now I have to add new validators and for that, I am planning to add substrate_validator_set and pallet_session. During OnRuntimeUpgrade what is the correct way to set Keys for pallet_session?

### Tasks

[bkchr]

There is currently no easy way. TBH, no one probably has done this before. You could create a pr to make this function public and write a custom OnRuntimeUpgrade that calls this function to set the keys.