feat: Timeline extension

[Hywan]

WIP, WIP, WIP. Don't take a look at this for the moment.

To Do

Runtime

First off, we need to be able to run a Wasm module. On all platforms, it's done with wasmtime. On iOS, it's done with JavaScriptCore.

• wasmtime
• JavaScriptCore
  • We use the javascriptcore.rs Rust crate for the binding, but some API were missing. The following patches were added:
  • feat: Add JSContext::global_object endoli/javascriptcore.rs#12
  • feat: Add JSObject::call_as_function endoli/javascriptcore.rs#13
  • fix: Remove &JSContext from JSObject::call_as_function endoli/javascriptcore.rs#14
  • feat: Implement JSObject::set_property and ::set_property_at_index endoli/javascriptcore.rs#15
  • chore: Introduce JSValue::new_string_inner to simplify code endoli/javascriptcore.rs#16
  • feat: Implement JSValue::new_array and other small clean up endoli/javascriptcore.rs#17
  • feat: Implement JSValue::new_typed_array_with_bytes endoli/javascriptcore.rs#18
  • feat: Implement JSObject::call_as_constructor endoli/javascriptcore.rs#19
  • feat: Implement JSValue::new_function endoli/javascriptcore.rs#20
  • feat: Improve the function_callback procedural macro endoli/javascriptcore.rs#21
  • fix: #[function_callback] can be used without javascriptcore_sys endoli/javascriptcore.rs#22
  • feat: Improve JSClass and add JSClassBuilder endoli/javascriptcore.rs#23
  • feat: Add JSString::len endoli/javascriptcore.rs#25
  • feat: Add JSTypedArray type endoli/javascriptcore.rs#26
  • fix: Add visibility on function and constructor callbacks endoli/javascriptcore.rs#27
  • fix: Add explicit imports for types endoli/javascriptcore.rs#28
  • feat(macros): Allow function/constructor callback to get generic parameters endoli/javascriptcore.rs#32
• Unify both runtimes behind a single unique API

For Wasm component model and WIT support, we use wasmtime built-in API, and JCO for JavaScriptCore. Contributions to those projects:

• feat: Allow --instantiation to generate non-async code bytecodealliance/jco#254
• chore: Make Clippy happier bytecodealliance/jco#255
• Use --js with --instantiation bytecodealliance/jco#273
• feat: lazily generate instanceFlags bytecodealliance/jco#275

Permissions

• Scan the imports of the Wasm modules to detect permissions
• Design a simple permissions system (which permissions are allowed or not)

ABI

To Do items aren't defined yet, but roughly:

• Define unique ABI that can be used from wasmtime and JavaScriptCore
• Define basic ABI for:
  • Timeline manipulation
  • network requests
  • key/value storage

Plug into the Matrix SDK

• Use the event handler API to plug the extensions

---

• Address https://github.com/vector-im/element-internal/issues/512