[Feature] feat(sol!)!: improve sol call bindings

[yash-atreya]

Component

sol! macro

Describe the feature you would like

Currently for SolCall's with no params or exactly one param we generate the following bindings:

sol! {
    function totalSupply() returns (uint256);
    function balanceOf(address) returns (uint256);
}

struct totalSupplyCall {}

struct balanceOf { owner: Address } 

Proposing the following changes:

// Unit struct
struct totalSupplyCall;

// Tuple struct 
struct balanceOf(pub Address);

Additional context

No response