Is your feature request related to a problem? Please describe.

I'm always frustrated when we can't have a system where quotas can't be changed by users. Take testnet, it's not intended to be a proper storage platform and yet there are no limits we can set there for users. Private networks may also want to have different roles for quota management.

Describe the solution you'd like

Check owner or alphabet witness in quota management methods of container contract depending on boolean netmap-stored setting. By default (mainnet) it's managed by owners.

Describe alternatives you've considered

Proxy calls/checks, additional contracts, different contracts depending on NNS.