[llvm] [llvm-cov] Export decision coverage to output json (PR #144335)

[Alan Phipps via llvm-commits]

evodius96 wrote:

> @evodius96 Oh, sorry, I overlooked that. Yes, I will adjust/add it. I assume I have to open a whole new PR, right?

No problem. You should be able to upload changes to the same PR; no need to create a new one.

https://github.com/llvm/llvm-project/pull/144335