Add support for elastic embedding sizes under 768 dimensions

[demoncoder-crypto]

Add support for elastic embedding sizes under the standard 768 dimensions

Description

This PR adds support for customizing embedding dimensions in text embedding models, similar to what's available in the Python API. Users can now request embeddings with dimensions of 128, 256, 384, 512, or 768 (default).

Changes

• Added dimensions parameter to EmbedContentRequest interface
• Updated formatEmbedContentInput to validate dimension values
• Added sample code demonstrating how to use elastic embedding sizes
• Updated README with documentation and examples
• Added unit tests for the new functionality

Testing

The implementation includes validation to ensure only supported dimension values (128, 256, 384, 512, 768) are used. The code has been successfully built and tested locally.

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