Update instantiate config command

[alpe]

There is currently no message/ command to modify the instantiate settings on code info except for gov (#796).
This functionality should be limited to the creator who uploaded the code initially.

This can be achieved by adding a new method to the AuthorizationPolicy and calling it in the keeper.setAccessConfig.
Also the change rules in #840 need to be taken into account

[ethanfrey]

There is currently no message/ command to modify the instantiate settings on code info except for gov (#796).
This functionality should be limited to the creator who uploaded the code initially.

I am not sure if we want this. The other approach in #840 would break / become fragile with the ability of a non-governance actor to modify this

[ethanfrey]

If we do this, it should only be the actor who can instantiate the code, not the creator.

Basically, allowing someone with that ability to transfer it or share it

[ethanfrey]

Removing this from v0.29 milestone as not urgent and needing more discussion first

[ethanfrey]

Adding to v0.31.0 as part of the UX around permissioning.