[clang] Add isTrivial() and isTriviallyCopyable() AST matchers (PR #90634)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> I remember back in the day that adding new matchers was a problem because it grew the size of the files beyond some supported compiler's limit.
> 
> Could @AaronBallman or someone else knowledgable about this(cc @kadircet) take a look and confirm adding matchers is fine now?

We generally only add matchers when there's a need for them to reside in-tree (e.g., a few clang-tidy checks will use them); otherwise we recommend that folks define their own custom matchers. The reason is mostly because compile time overhead for compiling ASTMatchers.h is... huge... due to the template instantiations, so we usually want there to be a need before adding any.

Is there a planned need here?

https://github.com/llvm/llvm-project/pull/90634