chore: Remove .idea directories from the sample apps

[vincetran]

• PR conforms to Pull Request guidelines.

Issue #, if available: N/A

Description of changes: Noticed during development that my Android Studio instance was modifying .idea files in the sample apps. From the .gitignore, it looks like we want to ignore them but the regex was only checking .idea in the top-level dir. Updated that regex and removed the existing .idea folders from the Auth and Liveness sample apps.

How did you test these changes?
After making the change in the .gitignorefile, made a .idea folder in a different folder and creating some files to make sure none of them were picked up by git.

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.