fix(testing): handle snapshot filepaths for jest

[rwaskiewicz]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Unit tests (npm test) were run locally and passed
• E2E Tests (npm run test.karma.prod) were run locally and passed
• Prettier (npm run prettier) was run locally and passed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

cf42114 created a regression where files named e2e.ts.snap would not be picked up correctly by the test runner

What is the new behavior?

this commit updates the testing regex in our jest base configuration to
handle files such as testing snapshots - those that contain 'spec.ts'
(or a similarly acceptable file extension for tests), but do not end
with that extension. For example, my-component.test.ts.snap

this fixes a regression introduced in cf42114

Does this introduce a breaking change?

• Yes
• No

Testing

I pulled this branch, built this branch, and generated a tarball: npm ci && npm run build && npm pack

Within Ionic Core, I installed my tarball in ionic-framework/core from the build command above, and verified the correct number of tests were run (verifying against #3277 results from late last week)

I also tested this in a local (small) stencil project.

First, let's create a project and verify we can run tests:

npm init stencil@latest component snap
cd snap
npm i && npm t

Those tests pass, let's add a .snap file to verify the issue:

touch src/components/my-component/my-component.spec.ts.snap
npm t

Returns a warning that we found a test file without any tests in it. Let's install our tarball to verify it fixes it:

npm i <TARBALL>
npm t

🎉