Fix dropless MOE, add tests for sparse linear,

[jlamypoirier]

✨ Description

Fix: #303

• Set triton version to 3.1.0 since later ones have bugs that break dropless MOE.
• Add tests for sparse matmul. They don't actually catch the bug in 3.3.0 and 3.3.1, which must involve a more specific corner case (ex. for specific dimensions, stride, dtype).
• Skip unnecessary triton autotune in tests. (Ex. added tests go from ~5s to ~0.5s)
• Move functional tests to their own directory.

🔍 Type of change

Select all that apply:

• 🐛 Bug fix (non-breaking change that addresses a specific issue)
• 🚀 New feature (non-breaking change that adds functionality)
• ⚠️ Breaking change (a change that could affect existing functionality)
• 📈 Performance improvement/optimization (improves speed, memory usage, or efficiency)
• 🛠️ Code refactor (non-functional changes that improve code readability, structure, etc.)
• 📦 Dependency bump (updates dependencies, including Dockerfile or package changes)
• 📝 Documentation change (updates documentation, including new content or typo fixes)
• 🔧 Infrastructure/Build change (affects build process, CI/CD, or dependencies)