Implicit segmentation support

[petermasking]

We currently use an explicit segmentation model that treats anything not specified in the segment configuration as a common module. With the addition of support for index files (#572) and fractional segmentation (#597), we can now use index files to re-export from other modules, simplifying segmentation. While this approach works without issues, it is not yet very efficient.

For example, consider two modules with index files that are both in the same segment:

First module

// src/first/a.ts

export async function a()
{
    /* ... */ 
}

// src/first/index.ts

export { a } from './a';

Second module

// src/second/b.ts

import { a } from '../first';

export async function b()
{
    return a();
}

// src/second/index.ts

export { b } from './b';

Segment configuration

{
    "./first": { "a": { "access": "public" } },
    "./second": { "b": { "access": "public" } }
}

In this case, we’d expect function b to import the actual implementation of function a since they are in the same segment. However, this isn’t the case because the src/second/b.ts file itself isn’t segmented; only the index file that re-exports it is. This causes the remote module to be imported, adding unnecessary overhead.

To avoid this, we aim to include re-exported modules from segmented modules in the segmentation process.