[FR] Add Real-time Cryptocurrency Data Provider Integration

Problem Statement

Currently, the OpenBB Platform has limited real-time cryptocurrency data sources. While there are existing crypto providers, many users need access to more comprehensive real-time data for trading decisions, portfolio management, and market analysis.

Proposed Solution

Integrate additional real-time cryptocurrency data providers such as:

• CoinGecko Pro API for real-time prices and market data
• CryptoCompare API for historical and real-time data
• Messari API for fundamental crypto data (as mentioned in issue #5519)

Benefits

• Enhanced real-time data accuracy for crypto analysis
• Better coverage of altcoins and DeFi tokens
• Improved user experience for crypto traders and analysts
• Expanded data source options for reliability

Implementation Details

1. Create new provider extensions following OpenBB Platform patterns
2. Implement standard data models for crypto data
3. Add proper error handling and rate limiting
4. Include comprehensive unit and integration tests
5. Update documentation with new provider usage examples

Acceptance Criteria

• Real-time price data retrieval works correctly
• Historical data fetching is implemented
• Proper error handling for API failures
• Rate limiting respects provider limits
• Documentation is updated
• Tests achieve >90% coverage

Additional Context

This would complement the existing crypto extension and align with the platform's goal of providing comprehensive financial data access.