feat: add custom promopts for copilot

Author: peter-jerry-ye

.github/prompts/consistency-review.prompt.md

@@ -0,0 +1,26 @@
+---
+mode: agent
+model: GPT-4o
+description: Review the consistency between APIs
+---
+
+Your goal is to review the consistency between similar APIs. Ask for the type
+names (at least 2) if not provided.
+
+Find the definition of the type, figure out the directory it locates, and review the `pkg.generated.mbti` file.
+
+**Criteria**
+
+1. Clarity and readability of the interface definitions.
+2. Consistency in naming conventions and structure.
+3. Usability and functionality.
+
+**Guidelines**
+
+1. Only keep necessary APIs, such as those can only be defined internally to
+   achieve the best performance.
+2. Follow the existing naming convention of other programming language standard
+   libraries for familiarity, but prioritize the consistency.
+
+Be specific on the review. Point out the API that is problematic, together with
+arguments, and suggested improvements.