[clang] [Clang][UnsafeBufferUsage] Warn about two-arg string_view constructors. (PR #180471)

[Ziqing Luo via cfe-commits]

ziqingluo-90 wrote:

> I investigated isPtrBufferSafe but kept the specialized logic for string_view. The current helper is too strict

This is fine. I want the function to be the unified place for defining safe patterns for a buffer pointer and its associated size expression, so we only write them once. We may need some refactoring later to achieve this.

https://github.com/llvm/llvm-project/pull/180471