fix(build): ensure typescript declarations are built with correct path

[austingreendev]

Description

#996 found that our TS declarations are including their relative path (including package name) inside their type directories.

I was able to trace this back to #984 specifically this change.

By referencing the *.ts file (/src) rather than the compiled dist this is changing the declaration paths somehow. By updating this reference the TS declarations have the expected structure.

Checklist

• 👌 design updates are Garden Designer approved (add the
  designer as a reviewer)
• 🌐 demo is up-to-date (yarn start)
• ⬅️ renders as expected with reversed (RTL) direction
• 🤘 renders as expected with Bedrock CSS (?bedrock)
• ♿ analyzed via axe and evaluated using VoiceOver
• 💂‍♂️ includes new unit tests
• 📝 tested in Chrome, Firefox, Safari, Edge, and IE11

[coveralls]

Coverage remained the same at 95.727% when pulling 48835b6 on agreen/fix-ts-declarations into 22d91d7 on main.