[Feature Request] Add support for AWS Bedrock API

[FANTASYSSL]

Currently, the project supports several LLM providers, but it lacks integration with AWS Bedrock. Many enterprise users prefer AWS Bedrock for its security, scalability, and access to models like Claude 3, Llama 3, and Amazon Titan.

I would like to see AWS Bedrock integrated as a supported model provider. This would likely require adding the following configuration fields in the settings UI:

AWS Access Key ID
AWS Secret Access Key
AWS Region (e.g., us-east-1)
Model ID (e.g., anthropic.claude-3-sonnet-20240229-v1:0)

Using a local proxy or custom API base, but native support would provide a much smoother user experience and better support for AWS's authentication mechanism.

AWS Bedrock documentation: https://docs.aws.amazon.com/bedrock/