[fix] Add missing parameters for customs item

[nwithan8]

Description

Add missing optional parameters (e.g. "code", "manufacturer", "eccn") to customs item parameter set.

Closes #567

Testing

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)

[Justintime50]

This adds it to the parameters, but can they pass this via the older dict approach too?

[nwithan8]

This adds it to the parameters, but can they pass this via the older dict approach too?

Yes, anyone can pass any parameters via the legacy dictionary method.