MSBuild Task needs explicit control whether to build remaining projects on error

The current behavior of the MSBuild task in non-parallel .sln build is to not build remaining projects after a project failed to build.

However if you specify `/m` then it seems that MSBuild will build all projects even if some of them failed to build.

It would be nice to introduce a task parameter such as `BuildRemainingProjectsOnError` that defaults to false to preserve the default behavior, but that would allow to still build the remaining projects in single-node builds even if previous project(s) have failed.

This is useful when you are gathering .csc information for example and don't care so much about the build results. You still want to collect all Csc invocations even in case of errors.