[llvm] [Coverage] Move SingleByteCoverage out of CountedRegion (PR #110966)

[Ellis Hoag via llvm-commits]

https://github.com/ellishg commented:

Looks good overall. I assume if you added a test case in https://github.com/llvm/llvm-project/pull/110972 that would also cover this code.

https://github.com/llvm/llvm-project/pull/110966