feat: use `gpt-tokenizer` (#1352)

.changeset/friendly-chicken-switch.md

packages/env/package.json

packages/env/src/tokenizers/node.ts

packages/env/tests/tokenizer.test.ts

...es/llamaindex/e2e/examples/waku-query-engine/package.json

.../llamaindex/e2e/examples/waku-query-engine/vite.config.ts

packages/llamaindex/package.json

packages/llamaindex/src/next.ts

pnpm-lock.yaml