RCP-240227A: Make timestamp part of genesis

[dr-orlovsky]

layers: consensus, standard library
consensus: pushback

Today genesis doesn't provide a way to define a moment of the contract issue (genesis creation).

Specific schemata have to define a dedicated global state and require genesis to provide it. This information can also be exposed to wallets via interfaces, like RGB20, 21 etc.

No support for timestamps in genesis combined with a need to provide this information for nearly each type of contract leads to a lot of boilerplate code and makes the lives of contract developers and issuers harder.

I propose to introduce timestamp as a part of genesis, and provide an API for it in stdlib, independently from the interface.