feat(nargo): add skeleton of composite types in template input tomls

[TomAFrench]

Related issue(s)

Resolves #

Description

Summary of changes

Consider the program

struct MyStruct {
  d1: Field,
  d2: [Field; 2],
}

fn main(a: Field, b: u32, c: [Field; 2], d: MyStruct, e: bool) {}

Currently this gets templated into Prover.toml by nargo check as

a = ""
b = ""
c = []
d = ""
e = ""

This adds unnecessary friction as d is really a table and will need to be moved down to the bottom of the file and the user is responsible for adding all of its fields. This can lead to an annoying back and forth with ABIErrors when trying to fill in this file.

To address this, we now template each AbiType recursively to produce

a = ""
b = ""
c = ["", ""]
e = ""

[d]
d1 = ""
d2 = ["", "", ""]

Users no longer have to rebuild their struct types or worry about lengths of array, just replace anywhere there's a "" with an actual value.

Dependency additions / changes

Test additions / changes

I've added a test as a smoke test for this.

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Documentation needs

• This PR requires documentation updates when merged.

Any examples of generated Prover.toml files in the docs need to be updated if they contain structs or arrays.

Additional context

[Savio-Sou]

Prover.toml examples in the docs do not involve structs or arrays.

Thanks for flagging nonetheless. Removing doc needed label now.