API fails to build monorepo with yarn workspaces

**Describe the bug**
After repackaging my multirepo project into a monorepo based on yarn workspaces, I noticed the app won't deploy to Azure Static Web Apps anymore. The issue is that when building the Functions app yarn does not pick up one of the dependencies is found in one of the yarn workspace packages. As a result it tries to find the package in the public registry and fails.

**To Reproduce**
See [this test repo](https://github.com/jeroenvdmeer/aswa-yarntest) I've created based on my setup.

**Expected behavior**
Similar to my development setup: after building the Functions app should be able to run.

**Screenshots**
More details can be found in [my test repo](https://github.com/jeroenvdmeer/aswa-yarntest).


**Additional context**
One part I'm a bit concerned about is that I added a dummy yarn.lock file in the `packages/api` folder [to trigger Oryx to use yarn instead of npm](https://github.com/microsoft/Oryx/issues/1073). The lockfile didn't hinder me to build the Functions app locally, but if there are better ways to trigger Oryx to use yarn, I'm happy to give them a try to rule out this could affect the build process.