Extensionless imports broken under 'composite project' builds

[davidtaylorhq]

Typescript supports extensionless imports like this:

import MyComponent from "./my-component";

This works for gts/gjs targets in Glint under Typescript's default project mode:

❯ pnpm ember-tsc -p . 
# ✅ succeeds

However, when running using Typescript's --build mode, extensionless imports of .gjs and .gts files fail to resolve. Extensionless imports of .js and .ts files continue working.

❯ pnpm ember-tsc -b  
js-entry.js:3:27 - error TS2307: Cannot find module './my-js-component' or its corresponding type declarations.

3 import MyJsComponent from "./my-js-component";
                            ~~~~~~~~~~~~~~~~~~~

ts-entry.ts:1:27 - error TS2307: Cannot find module './my-ts-component' or its corresponding type declarations.

1 import MyTsComponent from "./my-ts-component";
                            ~~~~~~~~~~~~~~~~~~~


Found 2 errors.

Full reproduction here: https://github.com/davidtaylorhq/glint-project-test