Improvements to moving source files

[dsherret]

This is talked about a bit in #199.

Right now, sourceFile.move:

1. Needs to update...
   • import equals declarations.
   • [ ] Referenced files in the tsconfig.json.
   • [ ] <reference ... /> tags.
   • Dynamic imports ex. await import("./test");
2. EDIT: DONE! - Does not use a graph to figure out the dependent files (This would also be nice as a standalone feature as well).
   • I have been looking at getAllDependencies in BuilderProgram, but this seems dependent on compilation (ex. returning all files when specifying the outFile or out compiler options). I think I'm just going to build up my own lazy graph... not so hard to do.

[dsherret]

I was just looking with ts-ast-viewer and there is an internal imports property on ts.SourceFile that has all the string literals for any imports. This would be way faster to use! It's ok to rely on this internal property because there will be tests in this library that would catch when this changes.

Edit: Done.