refactor: remove params dependency on modules

[ARR4N]

Why this should be merged

Note

This will probably be replaced by #1271

Importing core/types from precompile/{modules,contract} results in a circular dependency because types -> params -> precompile/modules -> precompile/contract -> types.

How this works

As you can see from the commit history, this took a lot of experimentation! The final result:

params only depended on modules for unmarshalling JSON, so all such functionality is abstracted into a new paramsjson package. To avoid having to import paramsjson, the params package instead exposes params.RegisterJSONUnmarshalers(), which allows paramsjson to inject its functionality in an init() function.

The paramsjson package doesn't export anything, and should instead be blank _ imported. This is similar to registering SQL drivers. The _ import has been added where necessary.

The alternative of using paramsjson.Unmarshal() in lieu of json.Unmarshal() proved problematic because of the number of other types with params.ChainConfig and other problematic types as fields.

Methods on *params.ChainConfig that relied on the modules package were only using it to access all precompile addresses. precompileconfig.Config now exposes the precompile's address, and the ChainConfig methods only know of the addresses that they receive as arguments or carry in GenesisPrecompiles and UpgradeConfig fields.

How this was tested

All existing CI tests.

How is this documented

Standard Go comments.