IsReachable is the inverse of IsLimited, but the implementation is duplicated (DRY)
- Changed the implementation accordingly.
- Added unit tests to document behavior and relationship
- My modification in net.cpp applies only to IsReachable.
- Applied clang-format-diffpy
Created new pull request to avoid the mess with: #15044
Checked with supposedly conflicting PRs mentioned in the old PR. No conflicts with the specific changes in this PR.