[clang] [clang] Instantiate attributes on other decl types (PR #115924)

[Eric Astor via cfe-commits]

ericastor wrote:

> The change is reasonable, but I need to see tests for each of the types.
> 
> In general, we've had the attitude of "we can enable this instantiation once we see examples of it being useful", so we need tests to make sure it is instantiated, AND that it is useful.

This makes a lot of sense... but I'm not sure there's currently a way to write a FileCheck test for (e.g.) attributes on labels, which is actually my motivating case here. It'd be a pretty big change to start dumping label attributes in text AST dumps when the LabelDecl isn't even shown. Any suggestions?

https://github.com/llvm/llvm-project/pull/115924