Unable to point testEnvironment to a node module in stencil.config.ts

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Stencil version:

 @stencil/core@1.12.2

I'm submitting a:

[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://stencil-worldwide.herokuapp.com/ or https://forum.ionicframework.com/

Current behavior:
Tests do not run when pointing testEnvironment to a node module in stencil.config.ts. Jest looks for the module in /path/to/my/project/stencil.config.ts/<module name>

Expected behavior:

Tests should run when pointing testEnvironment to a node module in stencil.config.ts as described in Configuring Jest Guide.

Steps to reproduce:

1. Set testEnvironment to "jsdom" in stencil.config.ts.
2. Run tests with npm test
3. Observe error:

[ ERROR ]  runJest: ● Validation Error: Test environment
           C:/path/to/my/project/stencil.config.ts/jsdom
           cannot be found. Make sure the testEnvironment configuration option
           points to an existing node module. Configuration Documentation:
           https://jestjs.io/docs/configuration.html

Related code:
I set testEnvironment to "jsdom" in stencil.config.ts like this:

  testing: {
    testEnvironment: "jsdom"
  }

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I've opend a PR for this: #2534