Promptwatch

- better chat messages tracking

- change implementation of comparing instances in find_templates_recursive, since there is a weird implementation in langchain that causes error even for testing instances

- much better semantic caching for registered templates... now viable option for Agents and many other scenarios !
- adding option to recursively register all templates automatically using `find_templates_recursive` or `find_and_register_templates_recursive`
- added possibility of using API_KEY parameter in UnitTests [GH feature request 9](https://github.com/blip-solutions/promptwatch-client/issues/9)

- fixed registering templates for LLMChain subclasses [GH Issue 7](https://github.com/blip-solutions/promptwatch-client/issues/7)

- add some sanity checks for common mistakes

- introduction of UnitTests
- support for initialization of tracking_project from PROMPTWATCH_TRACKING_PROJECT Env variable
- refactoring of the file structure