feat: simplify callback manager (#1027)

.changeset/clean-games-hear.md

.changeset/tall-maps-camp.md

.changeset/tricky-candles-notice.md

examples/anthropic/agent.ts

examples/multimodal/context.ts

examples/multimodal/rag.ts

examples/qdrantdb/preFilters.ts

examples/recipes/cost-analysis.ts

packages/core/src/global/index.ts

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

packages/core/src/utils/wrap-llm-event.ts

packages/core/tests/event-system.test.ts

...ex/e2e/examples/nextjs-node-runtime/src/actions/openai.ts

packages/llamaindex/e2e/node/utils.ts

packages/llamaindex/src/agent/base.ts

packages/llamaindex/src/agent/types.ts

packages/llamaindex/src/agent/utils.ts

packages/llamaindex/src/cloud/LlamaCloudRetriever.ts

packages/llamaindex/src/index.edge.ts

packages/llamaindex/src/indices/vectorStore/index.ts