[ShopifyVM] add functions integration test with github workflow

[mssalemi]

Background

Added test through a Github Workflow to test that all function extension templates built and run successfully

Solution

• validates the function can be built -> dependency install + compilation
• validates the function can run -> tests execute the run() functions
• helps avoid package update breakage -> runs on every change

Other Options

• add integration tests to each function template (this add alot of files)
• standalone integration test script (this requires have a integration-tests folder and adding commands to the package json to run, this doesn't seem to follow any pattern in this repo, but is possible

Checklist

• I have 🎩'd these changes
• I have squashed my commits into chunks of work with meaningful commit messages