How to force get emit output?

First of all, great project. Thanks a lot!
```ts
const service = project.getLanguageService()
const outputFiles = project
.getSourceFiles()
.map(sourceFile => {
const temp = service.getEmitOutput(sourceFile, true)
const emitOutputFiles = temp.getOutputFiles()

return emitOutputFiles
})
```
Hello! I use `service.getEmitOutput` in the way above. But when my code modified and rerun `service.getEmitOutput`, **the emit output not change**.

And I found that the emit process was skipped(Result of `temp.getEmitSkipped()` was true). How can I solve this problem?

And I found `LanguageService` in ts has `forceDtsEmit` options for `getEmitOutput`, can I use it?

https://github.com/microsoft/TypeScript/blob/8e5e2e08ead119910d6eb177eab9beb84e3ab311/src/services/types.ts#L551

Start with the service.getEmitOutput call, temp.getEmitSkipped(), and the TypeScript LanguageService getEmitOutput declaration linked in the issue. Reproduce a second emit after modifying a project source file, then trace the ts-morph entry point to determine whether the forceDtsEmit option is supported. Done means the supported way to obtain refreshed output is established and covered by an appropriate test or documentation.

Written by the indexing model from the issue text.