feat(dart_frog): add tryRead method to RequestContext

[mtwichel]

Status

READY

Description

Closes #1651. Adds a tryRead function to the RequestContext that works exactly like read, but instead of throwing a StateError when a provided value isn't found, it return null. This is useful for objects that may or not be provided depending on certain factors, like a User being provided only if they are authenticated. The change has also been reflected in the docs site.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[alestiago]

Nit: If we end up adding tryRead I think we should modify the implementation to not catch the StateError, but instead implement tryRead so it does what read is doing right now but without the null check to avoid creating an additional StateError object when using tryRead. We could then base the read implementation on tryRead for code sharing.