Add mix notebook task for Livebook attached to dev node

Run `mix notebook` for instructions to start Livebook at localhost:8081
connected to the running Phoenix node with full Repo/Scorer access.

lib/mix/tasks/notebook.ex

@@ -0,0 +1,27 @@
+defmodule Mix.Tasks.Notebook do
+  @shortdoc "Start Phoenix + Livebook at localhost:8081/notebooks/algorithm_analysis.livemd"
+  @moduledoc false
+  use Mix.Task
+
+  @impl Mix.Task
+  def run(_args) do
+    hostname = :inet.gethostname() |> elem(1) |> List.to_string()
+    cookie = "microwaveprop_notebook"
+    node = "prop@#{hostname}"
+
+    IO.puts("""
+    Start Phoenix with a node name first:
+
+        iex --sname prop --cookie #{cookie} -S mix phx.server
+
+    Then in another terminal:
+
+        LIVEBOOK_NODE=#{node} LIVEBOOK_COOKIE=#{cookie} livebook server \\
+          --port 8081 \\
+          --default-runtime attached:#{node}:#{cookie} \\
+          --open notebooks/algorithm_analysis.livemd
+
+    Livebook will be at http://localhost:8081
+    """)
+  end
+end