Smart Contracts: Http library module

[bchamagne]

Description

Implement AEIP-20.
Fixes #1161

• Update documentation
• Update AEIP with error codes

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Unit tested

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[bchamagne]

Not working in Smart Contract Playground.

• Use Mint in a task to be able to use the Http module from inside a busy process