[dart2wasm, typed_data] Support efficient WasmArray reinterpretation. #64256

We can't support typed data wasm performance parity with VM targets because we can't reinterpret a gc wasm array as an array of a different value type than the one it was constructed as.

There's a wasm proposal on the way that attempts to fix that: WebAssembly/multibyte-array-access#5

Efficient SIMD on wasm targets #64170 is blocked on this.

• We should keep an eye on that proposal and make sure it covers our use case
• We need to have a systemic way for opting-in to proposals (same for e.g. [dart2wasm, typed_data] Support for Relaxed SIMD. #64216)

The proposal can be found here: https://github.com/WebAssembly/multibyte-array-access/blob/main/proposals/multibyte-array-access/Overview.md#supported-instructions

@mkustermann It looks like the current proposal covers our use cases, but you might want to take a look, too, before it is finalized.