Support declarationMap output

[lukasIO]

Describe the feature

I couldn't find a way to make unbuild generate declarationMaps in addition to the types (and regular sourcemaps).
Sorry if I missed this, but would be great to add this to allow "Go to definition" in IDEs to actually jump to the TypeScript source code.

Additional information

• Would you be willing to help implement this feature?

[drwpow]

I’d be willing to help with a PR!

[productdevbook]

Hi, dear @lukasIO. You should set sourcemap: true in build.config to enable sourcemap support. unbuild does not infer from tsconfig.json. #348

[lukasIO]

@productdevbook thanks, but this is about declarationMaps not sourcemaps. I can get sourcemaps to work just fine, but declarationMaps are missing