test: move integration tests to dart

[vaind]

📜 Description

• moves integration tests to dart
• adds caching so it's faster in CI
• runs integration tests locally as part of dart test
• caches builds locally based on flutter version

💡 Motivation and Context

In preparation for changes in #277 and #173, moving integration tests to dart so that they're easier to extend.

also updated linux tests so:
closes #161
closes #164

💚 How did you test it?

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated the docs if needed
• All tests passing
• No breaking changes

🔮 Next steps

[buenaflor]

nice 👍