[types]: unify duplication of JSON-RPC types

[niklasad1]

The types have often two different version of the same type, one with allocation and one without allocation,

Ideally, these should be unified to decrease to technical debt and simplify the testing situation.

[dvdplm]

I think this has been partially resolved by various refactorings since 0.2. I'm going to close this one and we can open further issues down the line for any remaining duplicated types.