Add Bedrock Cohere Embedding Model

[Anantha-Kandrapu]

Validations

• [X] I believe this is a way to improve. I'll try to join the Continue Discord for questions
• [x] I'm not able to find an open issue that requests the same enhancement

Problem

Currently Cohere embedding models are not supported through bedrock client. It would be great to have cohere embedding model along side current amazon.titan-embed-text models

Solution

Add a new BedrockCohereEmbeddingsProvider to the existing embeddings. Only request and response needs different data structures.