Allow using project files together with --library

[keyboardDrummer]

Changes

• To enable smoothly working with multiple projects inside a single repository, Dafny now allows using a Dafny project file as an argument to --library. This does the following:
  1. Call dafny build -t:lib using the project file to get a doo file. In the future we plan to let this be a NOOP if the right build file is already there.
  2. Replace the usage of the project file in the origin call to dafny, with this doo file.
• Extract code from DafnyFile.CreateAndValidate into methods
• When parsing a file, correctly pass parse options to included files. This does not have any particular affect because only doo files are passed with different options, and those do not use includes. However, doing this does seem more correct and it was useful previously, so I'll keep it in.
• Move ReadsClausesOnMethods option code
• Do not let project files include themselves through something like includes = ["**/*"]

How has this been tested?

• Add the CLI test projectAsLibrary.dfy

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

[keyboardDrummer]

We have to pass --library %S/wrappersLib.dfy as well because it' a dependency of our dependency.