Support newer Bedrock models

[mongodben]

Please add support for the following models available on AWS Bedrock:

1. us.mistral.pixtral-large-2502-v1:0
2. us.meta.llama4-scout-17b-instruct-v1:0
3. us.meta.llama4-maverick-17b-instruct-v1:0
4. us.amazon.nova-premier-v1:0
5. us.deepseek.r1-v1:0