Clean working directory before each build option

Some workflows, in particular with a manual build, may benefit with the addition of a "Clean working directory before each build" option on the Miscellaneous tab when configuring a job.

An example is where a manual stage in a build plan uses artifacts from a previous stage. When the manual stage runs there may be leftover files from previous builds which prevents clean compilation. Customers may not want to clean the working directory after the build in case a problem occurs and results need to be reviewed.