fix(core): preserve WebAssembly streaming callback across new contexts (#34679)

WebAssembly.compileStreaming and WebAssembly.instantiateStreaming broke
after creating a new context with node:vm (e.g. via happy-dom's
new Window()) or after attaching the inspector. Subsequent calls
rejected Response arguments with "WebAssembly.compile(): Argument 0 must be a
buffer source", even though the same code worked moments earlier and works in
Node.

The cause is in deno_core. The streaming callback is installed lazily
from JS, so deno_core set the --wasm-test-streaming V8 flag to force V8 to
install compileStreaming/instantiateStreaming at all. That flag also
makes V8 reset the isolate-wide streaming callback to its own testing callback
every time it re-creates the WebAssembly object, which happens on every
new context (node:vm) and when the inspector attaches. The testing callback
only accepts BufferSource arguments, hence the error.

This installs the streaming callback natively at isolate creation, the
same way Node does, and drops the --wasm-test-streaming flag so V8 no longer
overwrites it. op_set_wasm_streaming_callback now only stores the JS
handler; the v8-level callback is set once and survives later context creation.

Fixes #34677
Fixes #21508