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

[Alan Phipps via llvm-commits]

https://github.com/evodius96 approved this pull request.

LGTM.  Do you have access to merge it?  If not, I can attempt to merge it on your behalf.

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