Amazon Q: Add configuration option to save custom prompts in workspace directory #7984

Problem

Currently, Amazon Q custom prompts are saved globally in ~/.aws/amazonq/prompts. This creates limitations for:

• Project-specific prompt management
• Team collaboration through version control
• Environment isolation between different projects

Expected behavior

Add a configuration option amazonQ.promptsLocation to allow users to choose where custom prompts are stored:

• "global" (default): Current behavior using ~/.aws/amazonq/prompts
• "workspace": Save prompts in workspace root directory (e.g., .amazonq/prompts)

Use cases

1. Project-specific prompts: Different projects may require tailored prompts for their specific domain, coding standards, or requirements
2. Team collaboration: Share custom prompts with team members through version control
3. Environment isolation: Keep development, staging, and production prompts separate

Related

This addresses similar needs as the closed issue #6415 but focuses specifically on the storage location configuration rather than workspace-local prompt configuration.