[llvm] [cross-project] Add tests for LLDB data-formatters for llvm::ArrayRef (PR #173238)

[David Blaikie via llvm-commits]

dwblaikie wrote:

> * the GDB formatter tests put all the test cases in one monolithic test file, whereas I'm planning on having one test-file per LLVM container.
> * the GDB formatter tests currently only get run if LLVM was built with debug-info. Not sure we have any build-bots out there running this configuration. In this patch we rely on just the debug-info from the LLVM headers (see latest commit). That way the tests get more consistently run (at least our public macOS buildbot runs the cross-project-tests in Release+Asserts).

Both those things seem fine by me - given the gdb tests have llvm and mlir coverage, you could consider an extra nested directory to group the llvm ones so mlir ones can go in another directory beside it, etc. But can also cross that bridge if/when we come to it. (I think the llvm one was also named after the library - `llvm-support` is the tests for the llvm/include/{Support,ADT} directories, for instance - so you could group even further with subdirectories `cross-project-tests/debuginfo-tests/llvm-prettyprinters/lldb/llvm/support/array.cpp`) But, yeah, no big deal. It'll grow as it grows and can be reorganized as needed.

https://github.com/llvm/llvm-project/pull/173238