Speed up inspect.signature() for Python functions

inspect.signature() builds a Signature whose every Parameter is constructed through the public Parameter constructor, which validates the name and kind on each call. When the parameters come from a function's own code object the names are already valid identifiers and the kinds are already the canonical constants, so that validation re-checks facts that are guaranteed to hold.

Signature introspection runs constantly in the ecosystem: web frameworks resolving view and dependency arguments, CLI libraries like click, pytest fixture wiring, and serialization and validation layers all call it per function, often at import time while wiring an application together.

Taking the signature of 400 real callables collected from popular packages (requests, click, jinja2, sqlalchemy, werkzeug, flask and others) takes 1.46 ms today and 1.16 ms when trusted-source parameters skip the redundant validation, 26% faster, with the public Parameter() constructor and its validation unchanged for every other caller.

Linked PRs

• gh-150823
• gh-157463

首先追蹤 inspect.signature() 經過 Signature 和公開 Parameter 建構函式的流程，著重於從函式程式碼物件取得的參數。將現有路徑和 Trusted-Source 路徑與 issue 中描述的 400-callable 基準進行比較，並驗證公開 Parameter() 的驗證維持不變，同時重現回報的效能改善。