* fix(bedrock/cohere): wrap embedding_types as list in map_openai_params
Bedrock Cohere expects embedding_types as a JSON array but
encoding_format was passed through as a raw string, causing:
Malformed input request: #/embedding_types: expected type: JSONArray, found: String
* test(bedrock/cohere): assert embedding_types is sent as JSON array
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Co-authored-by: Ishaan Jaffer <ishaanjaffer0324@gmail.com>