workingctx: call _dirstatestatus in status Rip out the call from workingctx.status to localrepo.status.

context: add private _dirstatestatus method This patch is a step forward in getting rid of needing to check 'parentworking' throughout the status method. Eventually, we will use the power of inheritance to do the correct thing when comparing the working directory with its parent. This method is mostly a copy from localrepo.status. The custom status method of workingctx will eventually be absorbed by the refactoring of localrepo.status to context.status but unfortunately we can't do it in one step.

committablectx: move status to workingctx This method was accidentally placed into the committablectx class. It contains logic for querying the dirstate so we move it to the correct class.