Spring-ai Add Amazon Bedrock Mistral model support.

AWS Bedrock Mistral: https://aws.amazon.com/bedrock/mistral/

Add supports for mistral.mistral-7b-instruct-v0:2, mistral.mixtral-8x7b-instruct-v0:1, mistral.mistral-large-2402-v1:0 and mistral.mistral-small-2402-v1:0 models.

Comment From: maxjiang153

re-implement with: https://github.com/spring-projects/spring-ai/pull/813