feat: initial streams support and convert to I/O module (#20)

* feat: initial implementation of native streams

* feat: introduce File API and new Blob

* fix: use real file size to prevent buffer overflow

* fix: tigthen WebSocket.send per spec

Author: grabbou

README.md

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+# Blob
+
+## Usage
+
+[TBD]
+
+## Differences with React Native's `Blob`
+
+- Can create `Blob`s from `ArrayBuffer`, `ArrayBufferView` too. With React Native, [you can only create Blob from string or another Blob](https://github.com/facebook/react-native/blob/af384a914a4e9ef6a5d25b00bc14b0483e5af879/packages/react-native/Libraries/Blob/BlobManager.js#L69-L73)
+- Each `Blob` has `text()`, `arrayBuffer()`, and `stream()` methods. With React Native, you can only access the contents of `Blob` via [custom `data` field](https://github.com/facebook/react-native/blob/af384a914a4e9ef6a5d25b00bc14b0483e5af879/packages/react-native/Libraries/Blob/Blob.js#L75-L82)
+- `Blob` does not depend on a native module. Uses `ArrayBuffer`s natively, thanks to Nitro Modules. With React Native, [Blob uses `RCTBlobManager` under the hood](https://github.com/facebook/react-native/blob/bd323929dc5be5666ee36043babec7d981a095dc/packages/react-native/Libraries/Blob/RCTBlobManager.h#L15) to create and hold references to the data.
+- `Blob` is automatically deallocated when no longer in use. [You don't have to `close()` it manually](https://github.com/facebook/react-native/blob/bd323929dc5be5666ee36043babec7d981a095dc/packages/react-native/Libraries/Blob/Blob.js#L122-L138)

docs/blob.md

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+# Networking
+
+## Usage
+
+[TBD]
+
+## Differences with React Native's `fetch`
+
+[TBD]
+
+## Differences with Expo's `fetch`
+
+[TBD]

docs/network.md

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+# Streams
+
+## Usage
+
+[TBD]