Add self-hosted prompts for flows

Add gpt and claude_3 prompts for the following:

• fix_pipeline_context

• fix_pipeline_create_plan

• fix_pipeline_execution

• commit_changes

• fix_pipeline_push_changes

• resolve_sast_vulnerability_context

• resolve_sast_vulnerability_execution

• resolve_sast_check_false_positive

• resolve_sast_evaluate_mr_readiness

• resolve_sast_vulnerability_commit_and_push

• validate_sast_vulnerability_agent_prompt

• sast_vulnerability_source_file_agent_prompt

• sast_vulnerability_lines_agent_prompt

• sast_vulnerability_report_agent_prompt

• sast_fp_detection_agent_prompt

• sast_post_results_to_gitlab_agent_prompt

• code_review_prescan