Add a function to compute a dependency tree

cryptol-remote-api/python/cryptol/file_deps.py

@@ -0,0 +1,12 @@
+def nestedFileDeps(getDeps, name : str, isFile : bool) -> Any:
+  done  = {}
+  start = getDeps(name, isFile)
+  todo  = start["imports"].copy()
+  while len(todo) > 0:
+    m = todo.pop()
+    if m in done:
+      continue
+    deps = file_deps(m, False)
+    todo.extend(deps["imports"])
+  return (start, deps)
+