[FEATURE] : Add rerank bedrock client configuration support

[marora90]

Description

Adds support for configuring Bedrock reranker clients with custom botocore.config.Config options. This enables users to customize connection timeouts, read timeouts, and retry behavior for bedrock reranking operations.

Changes

• Add bedrock_reranker_client_config parameter to ProcessorArgs class
• Update processors to use configured session and apply botocore Config
• Document the new parameter

Problem

Related issue: #427

Users previously had no way to configure timeouts and retries for Bedrock reranking operations

Testing

• Unit tests added/updated
• Existing tests pass (pytest)

Checklist

• Code follows existing style and conventions
• License headers present on new files
• Documentation updated (if applicable)
• No breaking changes (or clearly documented)

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