Adds macros to assist in running bot trees in ExUnit.

Create a test file as per the normal ExUnit process, for example, in test/my_project_test.exs:

defmodule MyProjectTest do
  @moduledoc false

  # This will set up ExUnit.Case, import `action` from BotArmy.Actions and
  # alias BehaviorTree.Node.  You can pass `async: true` just like with `use
  # ExUnit.Case` if you want to run this test file in parallel to other async
  # files (be careful of tests that mutate a global state!).
  use BotArmy.IntegrationTest, async: true

  alias MyProject.Actions.Sample

  # use this if you want a log file (applies to all tests in module)
  log_to_file()

  # use this if you use a custom bot module (applies to all tests in module)
  use_bot_module(MyProject.CustomBot)

  # normal ExUnit setup how ever you need
  setup do
    %{magic_number: 9}
  end

  # you can also setup/cleanup via a tree similar to using `test_tree`
  pre_all_tree "pre all" do
    Node.sequence([action(BotArmy.Actions, :log, ["Pre all ..."])])
  end

  # Run test trees with `test_tree`, which works very much like ExUnit's
  # `test`, except it will run the bot and pass or fail based on its outcome.
  #
  # Setting the `:verbose` tag will show all of the bot's logs for that test,
  # otherwise only errors will show.

  @tag :verbose
  test_tree "validate target number", context do
    Node.select([
      action(Sample, :validate_number, [context.magic_number]),
      action(BotArmy.Actions, :error, [context.magic_number <> " is an invalid number"])
    ])
  end

Note, if a tree takes longer than 1 minute to run, it will fail the test. You can set @moduletag timeout: n (or @tag timeout: n per test) to raise this limit.