Add Claude AI Integration

This issue tracks the implementation of an integration for **Anthropic Claude** in Elsa Workflows. The module should allow workflows to interact with Claude for AI-generated text responses and custom API calls.

## **Tasks**
- [ ] Create a new module: `Elsa.Integrations.AnthropicClaude`
- [ ] Implement **Workflow Activities**:
- [ ] **CreatePrompt** - Creates a new prompt based on a structured list of input messages.
- [ ] **MakeAPICall** - Performs an arbitrary authorized API call to the Anthropic Claude API.

- [ ] Add Unit Tests
- [ ] Add Documentation (`README.md`)

## **References**
- 📖 [Anthropic Claude API Docs](https://docs.anthropic.com/)
- 🛠️ [Anthropic Developer Resources](https://www.anthropic.com/)

## **Notes**
- This should follow the standard structure used for Elsa Integrations.
- The integration should support authentication via API keys.

## **Contributor Guidelines**
If you're interested in working on this issue:

1. Comment below to claim it.
2. Follow the [CONTRIBUTING.md](https://github.com/elsa-workflows/elsa-integrations/blob/main/CONTRIBUTING.md) guide.
3. Submit a PR referencing this issue.