Add constraint + parse json into Config
Second part of refactoring Clio Config; First PR found
[here](https://github.com/XRPLF/clio/pull/1544)
Steps that are left to implement:
- Replacing all the places where we fetch config values (by using
config.valueOr/MaybeValue) to instead get it from Config Definition
- Generate markdown file using Clio Config Description
Implementation of new config definition + methods + UT
Steps that still need to be implemented:
- Make ClioConfigDefinition and it's method to be as constexpr as
possible
- Getting User Config file and populating the values in ConfigDefinition
while checking for constraints on user values
- Replacing all the places where we fetch config values (by using
config.valueOr/MaybeValue) to instead get it from Config Definition
- Generate markdown file using Clio Config Description
