[AUDIO_WORKLET] Added support for MEMORY64 and 2GB heap (including tests)

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This is built on #22753 and expands on the tests in #23394 (which could also be split into their own PR, but they'll all fail due to the required changes).

It adds support for MEMORY64 to audio worklets and tests that:

• All the pointer offsets and maths now work with >2GB heap
• Everything works building with MEMORY64 and >4GB heap

The tests already prove out various buffer combinations using the INITIAL_MEMORY and GLOBAL_BASE flags.

For the code changes, besides parameters expecting BigInt it also needed any shifts removing from the offset calculations (signed shifts fail >2GB, unsigned >4GB).

The interactive tests can be run with:

test/runner.py interactive_2gb.test_audio_worklet_params_mixing
test/runner.py interactive64_4gb.test_audio_worklet_params_mixing

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What about the exsiting audio worklet tests in test_browser.py?

I'll try to take a look in the next days, they're definitely all failing because even 2GB tests should fail. One of a couple of examples here:

emscripten/src/lib/libwebaudio.js

Line 244 in 62304e2

options >>= 2;

Then for wasm64 the offset fails, e.g.:

emscripten/src/lib/libwebaudio.js

Line 246 in 62304e2

numAudioParams = HEAPU32[options+1],

The offset should be +2 since the entry before is a pointer.

A simple standalone test with just the noise generator is:

emcc -sAUDIO_WORKLET -sWASM_WORKERS -sASSERTIONS=2 -sWEBAUDIO_DEBUG -sINITIAL_MEMORY=2200mb -sGLOBAL_BASE=2gb -o index.html audioworklet.c

With this PR's changes so far it now works, but I've more to do so this is still draft.

(All the CI failures I see are LLVM version issues Passed as of 1b36c8d.)

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I wrote a test for the web audio parameters, creating a pair of descriptors and using the first to handle fading. It needs some tidying up but the important parts are done and it correctly gets the C structs to JS. Demo here:

https://wip.numfum.com/cw/2025-02-05/index.html

It only properly works in Chrome and Firefox so far (I'll look at it).

This single line does the fade-in/out:

emscripten/test/webaudio/audioworklet_params_mixing.c

Line 59 in 48361fd

param.setTargetAtTime((param.value > 0.5) ? 0 : 1, 0 /* same as context.currentTime */, 0.5);

And the mix is currently done with this:

emscripten/test/webaudio/audioworklet_params_mixing.c

Line 42 in 48361fd

outputData[i] += inputData[i] * params[0].data[(params[0].length > 1) ? i : 0]; // world's worst mixer...

As before, @sbc100, shall I create a new PR just for these tests? Then another PR that fixes running the tests?

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What about the exsiting audio worklet tests in test_browser.py?

All the AW tests are silently failing. I'll look at fixing them next.

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It looks like we already have interactive64 mode in test_interactive.py. Can you just add interactive64_4gb and interactive_2gb modes? (copy them from test_browser.py).

Done.