Restructure tool_use_package as pip-installable anthropic_tools package

[elias-jhsph]

Hey there,

I noticed that the tool_use_package is structured as a standalone codebase rather than a pip-installable package. Given the long list of dependencies and the fact that the code is still in an alpha state and not yet recommended for production use, this structure makes sense as it keeps the code simple and self-contained during the early experimental stages of the project.

However, I believe that reorganizing the codebase into a pip-installable package called anthropic_tools could provide some benefits, even at this early stage:

It would allow the code to be more easily shared and tested by others who are interested in experimenting with these tools and providing feedback.
It would establish a more modular and maintainable structure as the codebase grows and evolves.
It would provide a clear path towards publishing a stable, production-ready package in the future, once the tools have matured and are ready for wider use.
To be clear, this change is not about prematurely optimizing the package for production use, but rather about incrementally improving the developer experience and laying the groundwork for future growth.

I've taken care to ensure that these changes do not alter the core functionality of the code. The majority of the modifications involve updating import statements, file paths, and directory structures to align with Python packaging conventions.

I'm open to discussing any concerns or suggestions you may have regarding this change. Please take a look at the modifications and let me know your thoughts, keeping in mind the experimental nature of the project at this stage.

Thanks for your consideration!

This pull request involves a reorganization of the package structure to allow it to be pip installed from other projects. The key changes include:

1. Moving the tool_use_package directory to src/anthropic_tools and updating all relevant import statements.
2. Adding a LICENSE file matching the anthropic package license
3. Updating the README.md file to reflect the new package name (anthropic_tools instead of tool_use_package).
4. Adding a pyproject.toml file with project metadata, dependencies, and build system configuration to enable pip installation.
5. Moving and renaming files and directories to fit the new anthropic_tools package structure, without changing the content of most files.
6. Updating example code and paths in the EXAMPLES.md file.

Overall, this pull request focuses on restructuring the existing codebase into an installable Python package named anthropic_tools, without making significant changes to the functionality of the code itself.