Split up commit status results into more sections

[prakashsurya]

Right now, when a build and test cycle is triggered, the pull request will have a single "OpenZFS Regression Tests" status that is displayed which encapsulates the build, ztest, and zfs test suite sections of the entire cycle. It might be useful to split this up, such that a status is reported back to the pull request of each individual section.. e.g. there could be a section for the build, another for ztest, and one more section for the zfs test suite. This way, if only the ztest section fails, it's obvious that the build and zfs test suite sections passed without having to click into the Jenkins UI.