feat: align `response-synthesizers` & `chat-engine` module (#1169)

.changeset/ten-bottles-learn.md

examples/huggingface/embedding.ts

examples/huggingface/embeddingApi.ts

examples/lowlevel.ts

examples/multimodal/rag.ts

examples/prompts/promptMixin.ts

examples/readers/src/csv.ts

examples/readers/src/llamaparse-json.ts

examples/vectorIndexAnthropic.ts

examples/vectorIndexFromVectorStore.ts

packages/core/package.json

packages/core/src/global/settings/callback-manager.ts

packages/core/src/indices/prompt-helper.ts

packages/core/src/query-engine/base.ts

packages/core/src/query-engine/index.ts

packages/core/src/query-engine/type.ts

packages/core/src/response-synthesizers/base-synthesizer.ts

packages/core/src/response-synthesizers/factory.ts

packages/core/src/response-synthesizers/index.ts

packages/core/src/response-synthesizers/type.ts