Get Rid of nobuild, nolink, and alldeps (#2765)

* Removing the nobuild, nolink, and alldeps dependency types in favor of being explicit.
* This will help with maintenance going forward, as adding more dependency types won't affect existing declared dependencies in weird ways.
* default deptype is still `('build', 'link')`

lib/spack/external/_pytest/freeze_support.py

@@ -42,4 +42,4 @@ def _iter_all_modules(package, prefix=''):
             for m in _iter_all_modules(os.path.join(path, name), prefix=name + '.'):
                 yield prefix + m
         else:
-            yield prefix + name
+            yield prefix + name