Support project references

[ajafff]

Checklist

• Fixes: Support for project references / composite projects #369
• Added or updated tests / baselines
• Documentation update

Overview of change

Always pass projectReferences to ts.createProgram if available. That causes TypeScript to resolve declaration files of referenced projects instead of the source files.
Always exclude declaration files of referenced projects from linting.
Don't create a Program if it's known to not contain any file matching the specified glob patterns.
When -r or --references is enabled, follow all "references" recursively and lint each project once.

[ajafff]

TODO:

• pass references to createProgram API to actually resolve build outputs of referenced projects
• check if build outputs (.d.ts files) of referenced projects are linted with the referencing project (requires Expose getOutputJavaScriptFileName from tsbuild microsoft/TypeScript#26410)
• simplify exclusion of external files for composite projects by only looking at rootFileNames
• implement this feature behind a flag (allows linting only one project without linting referenced upstream projects)
  • if that flag is enabled but no project is specified, default to . instead of the current findup approach