Split std into different packages

[Kouteki]

Description

Split into different packages

Package name ideas (see related gist)

• chain - containing critical chain types, like Address, AddressList.
• chain/runtime - containing meta-VM functions, like CurrentRealm, PrevRealm, AssertOriginCall.
  • not runtime as it has a different API and usage than Go's runtime
• chain/banker - containing the Banker and Coin types, and related functions and methods to deal with the native banker.
• chain/params - containing the SetParamBool, SetParamString, ... types

The division into packages should help to reduce the scope of each package, helping us create modular packages. It's not definitive; some questions remain on where to put the Emit functions.

Why: at the time being, all Gno-specific functions are lumped together in a single, big std package. Naming packages like base, util or common is considered bad practice in Go, where instead packages should be more specific and be concerned with specific purposes.

Status: consensus.

References:

• META - splitting and refactoring std #1475 (comment)
• META - splitting and refactoring std #1475 (comment)

Meta issue: #1475