feat(nargo): remove misleading quotes in generated Prover.toml

[TomAFrench]

Related issue(s)

Resolves #

Description

Summary of changes

Currently running nargo check on a new project generates the Prover.toml file as below

x = ""
y = "[]"

This isn't ideal as unless users remove the quotes around the array, they'll get the error message Error: cannot parse a string toml type into Array { length: 2, typ: Field }.

This PR updates build_placeholder_input_map so that we get the generated toml file

x = ""
y = []

Dependency additions / changes

Test additions / changes

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.

Additional context