Implement type-safe primary keys across SDKs

This issue tracks reimplementing the work from stale PR #3476, which has been closed because it is too far out of date to merge directly.

Original pull request

• PR #3476: Implemented type-safe primary keys
• Original author: @egormanga

What the original PR was trying to do

Description of Changes * Note: based on (and includes) 2957. For a table like this: generates a type like that: Yet to make it treat the type as Identity. Perhaps a trait is needed instead of a newtype. Usage: * Resolves 3472. API and ABI breaking changes None. Expected complexity level and risk 3? Testing - [x] Module compiles - [x] Module publishes

Closure context

• I think we need to have a think about this one in the context of other languages. As written this would make Rust types inconsistent with the types in the other languages. Much like in #2957 we'd need to address this for all languages.

Reimplementation notes

• Reimplement this work on top of current master in a new PR.
• Keep the original PR linked as historical context and as a source of useful implementation ideas where still relevant.

Start by reviewing PR #3476 and comparing its approach with current master and the other SDKs. Identify the SDK-specific representations and compatibility constraints before defining the cross-language design. Done means a new PR reimplements type-safe primary keys consistently across all affected SDKs, with the relevant modules compiling and publishing as in the original PR.