fix: Add metadata to PDFs and use Uint8Array for readers content (#980)

.changeset/new-worms-teach.md

examples/readers/src/custom-simple-directory-reader.ts

packages/llamaindex/src/readers/CSVReader.ts

packages/llamaindex/src/readers/DocxReader.ts

packages/llamaindex/src/readers/HTMLReader.ts

packages/llamaindex/src/readers/ImageReader.ts

packages/llamaindex/src/readers/LlamaParseReader.ts

packages/llamaindex/src/readers/MarkdownReader.ts

packages/llamaindex/src/readers/PDFReader.ts

packages/llamaindex/src/readers/TextFileReader.ts

packages/llamaindex/src/readers/type.ts

...ges/llamaindex/tests/indices/json-to-index-struct.test.ts

packages/llamaindex/tests/readers/pdf-reader.test.ts