This simplifies and cleans up import map generation and adds support for turbopack, as well as the tsconfig `compilerOptions.basePath` property.
Previously, relative import paths looked like this:
```ts
import { TestComponent as ___ } from 'test/admin/components/TestComponent.js'
```
Paths like these will be resolved based on the `compilerOptions.baseUrl` path of your tsconfig.
This had 2 problems:
### baseUrl support
If your tsconfig baseUrl was not `"."`, this did not work, as the import map generator does not respect it
### Turbopack support
If Turbopack was used, certain import paths were not able to be resolved.
For example, if your component is outside the `baseDir`, the generated path looked like this:
```ts
import { TestComponent as ___ } from '/../test/admin/components/TestComponent.js'
```
This works fine in webpack, but breaks in turbopack.
## Solution
This PR ensures all import paths are relative, making them more predictable and reliable.
The same component will now generate the following import path which works in Turbopack and if a different `compilerOptions.basePath` property is set:
```ts
import { TestComponent as ___ } from '../../../test/admin/components/TestComponent.js'
```
It also adds unit tests
243cdb1901