[meta] refinement on contract extensions, system-contracts maintenace

[extraymond]

Info

description:
chain-extension and system contracts should be well maintained to have both static namesapce and static addresses. They should stay immutable from genesis.

required features:

• upgradable system-contracts, which can only be maintained by system-contract-deployer
• system-contracts deployment should be able to be deployed through gensis-config or on-initialize to automatically self delploy it on chain.
• system-contracts should have fixed addresses to allow easy developer integration
• chain-extension should be broken down into several smaller extensions which differ their behavior along their addresses, similar to precompile addresses

todo:

• #56
• #43
• #18
• #62