Add `Memorize` tool (#11722)
- **Description:** Add `Memorize` tool
- **Tag maintainer:** @hwchase17
This PR added a new tool `Memorize` so that an agent can use it to
fine-tune itself. This tool requires `TrainableLLM` introduced in #11721
DEMO:
https://github.com/Preemo-Inc/gradient-langchain-tool-demo/tree/6a9003d5db8db03673ad8b205f4d00cf0d96b56b
