chore: update the get examples matrix step to run some checks and be more readable

[jaredfholgate]

Description

This PR converts to PowerShell for readability and runs some checks on the examples folder:

• It checks whether any examples are present and throws an exception if not.
• It checks whether an example contain any .tf files before adding them as tests
• It checks for the .e2eignore and filters out those folders

Related:

• chore: remove mandatory default example folder name Azure-Verified-Modules-Grept#143
• chore: update composition to allow any folder name for default example Azure-Verified-Modules#1720

Type of Change

• Non-module change (e.g. CI/CD, documentation, etc.)
• Azure Verified Module updates:
  • Bugfix containing backwards compatible bug fixes
    • Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
    • The bug was found by the module author, and no one has opened an issue to report it yet.
  • Feature update backwards compatible feature updates.
  • Breaking changes.
  • Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• I did run all pre-commit checks