In this PR:
- Handle and require fully-qualified tool names `Toolkit.ToolName` in
the actor
Also, unrelated changes/fixes:
- Cleaned up the logic around actor secrets and `$ARCADE_ACTOR_SECRET`
- Removes experimental Flask actor for now
Note: Must be merged along with
https://github.com/ArcadeAI/Engine/pull/87
* Renamed `arcade_arithmetic` to `arcade_math`
* Deleted `arcade_github` toolkit for the next release. This will be
reintroduced later.
* Added 5 tools to `arcade_x` toolkit
- post_tweet
- delete_tweet_by_id
- search_recent_tweets_by_username
- search_recent_tweets_by_keywords
- lookup_single_user_by_username