[WASM-Export] Unable to use multiple rust GDExtensions at the same time

Hi,

Lately I've been working on a bigger game, and completed the refactor from C# to C++ and then I found this amazing library so I switched one more time to Rust.

Now, what I've had in mind was that I'd create a Shared, Client and Server project in Rust. Shared would have the Nodes that both projects need and Client and Server would be implementing the multiplayer features.

I created the following setup:
- godot (Godot Project)
- rust (Rust workspace)
- client (Rust project)
- server (Rust project)
- shared (Rust project)

Note: The `client` nor `server` projects do not depend on `shared` in `Cargo.toml`.

This setup is working terrific! I'm able to implement client specific features, and server specific features which will be connected using the shared nodes.

I can run this on my Linux machine, and confirm that it is working. However, I also target `wasm` so I tried getting that to work. Now, this isn't really working out.

I compile the workspace with `cargo +nightly build -Zbuild-std --target wasm32-unknown-emscripten` to WebAssembly, and this is going really well. But when I run the project, on Firefox I get an `out of memory` emscripten error (which it also does with a single Rust project, but only on Debug builds). When I run it on Chromium however, I get a big list of errors:
```
RuntimeError: Aborted(undefined). Build with -sASSERTIONS for more info.
at abort (tmp_js_export.js:9:8604)
at ___cxa_throw (tmp_js_export.js:9:425328)
at shared.wasm.panic_unwind::imp::panic::h7a89a72211144e04 (shared.wasm-10a1508e:0x42b504)
at shared.wasm.__rust_start_panic (shared.wasm-10a1508e:0x42b367)
at shared.wasm.rust_panic (shared.wasm-10a1508e:0x41d2e3)
at shared.wasm.std::panicking::rust_panic_with_hook::hc3a8cd21f77927d3 (shared.wasm-10a1508e:0x41d1d9)
at shared.wasm.std::panicking::begin_panic_handler::_$u7b$$u7b$closure$u7d$$u7d$::hb19be6fa9857ee61 (shared.wasm-10a1508e:0x41a5f5)
at shared.wasm.std::sys::backtrace::__rust_end_short_backtrace::h585b6ab617e4600a (shared.wasm-10a1508e:0x41a4bd)
at shared.wasm.rust_begin_unwind (shared.wasm-10a1508e:0x41c2a1)
at shared.wasm.core::panicking::panic_fmt::he773db1f33281f18 (shared.wasm-10a1508e:0x49a208)

  | onPrintError | @ | tmp_js_export.js:477
-- | -- | -- | --
  | abort | @ | tmp_js_export.js:9
  | ___cxa_throw | @ | tmp_js_export.js:9
  | $panic_unwind::imp::panic::h7a89a72211144e04 | @ | shared.wasm-10a1508e:0x42b504
  | $__rust_start_panic | @ | shared.wasm-10a1508e:0x42b367
  | $rust_panic | @ | shared.wasm-10a1508e:0x41d2e3
  | $std::panicking::rust_panic_with_hook::hc3a8cd21f77927d3 | @ | shared.wasm-10a1508e:0x41d1d9
  | $std::panicking::begin_panic_handler::_$u7b$$u7b$closure$u7d$$u7d$::hb19be6fa9857ee61 | @ | shared.wasm-10a1508e:0x41a5f5
  | $std::sys::backtrace::__rust_end_short_backtrace::h585b6ab617e4600a | @ | shared.wasm-10a1508e:0x41a4bd
  | $rust_begin_unwind | @ | shared.wasm-10a1508e:0x41c2a1
  | $core::panicking::panic_fmt::he773db1f33281f18 | @ | shared.wasm-10a1508e:0x49a208
  | $godot_ffi::binding::single_threaded::BindingStorage::set_initialized::haf88d1160aa08dd6 | @ | shared.wasm-10a1508e:0x3a7ebd
  | $godot_ffi::binding::single_threaded::BindingStorage::initialize::h06c546cc4398088b | @ | shared.wasm-10a1508e:0x3a7f1e
  | $godot_ffi::binding::initialize_binding::hec449e30c65edce2 | @ | shared.wasm-10a1508e:0x3b4174
  | $godot_ffi::initialize::hd3864843f056cfd2 | @ | shared.wasm-10a1508e:0x3b53dc
  | $godot_core::init::__gdext_load_library::_$u7b$$u7b$closure$u7d$$u7d$::h80e68cd7c7203dc9 | @ | shared.wasm-10a1508e:0x66696
  | $core::ops::function::FnOnce::call_once::h50d84be8fa3c9798 | @ | shared.wasm-10a1508e:0x70136
  | $std::panicking::try::do_call::h64bb311ea799ec2a | @ | shared.wasm-10a1508e:0x741fb
  | $__rust_try | @ | shared.wasm-10a1508e:0x734d8
  | $std::panicking::try::hcbde3b6f2bb9e296 | @ | shared.wasm-10a1508e:0x74088
  | $std::panic::catch_unwind::h4d4f243b6b7cf82f | @ | shared.wasm-10a1508e:0x72b00
  | $godot_core::private::handle_panic_with_print::h28362aa50547f00d | @ | shared.wasm-10a1508e:0x596e6
  | $godot_core::private::handle_panic::h7e38a629003b6b68 | @ | shared.wasm-10a1508e:0x59400
  | $godot_core::init::__gdext_load_library::h65f7301edd9aa8a6 | @ | shared.wasm-10a1508e:0x66521
  | $gdext_rust_init | @ | shared.wasm-10a1508e:0x5616f
  | $func58011 | @ | 0aaeb74a:0x2599747
  | $func58034 | @ | 0aaeb74a:0x259dff6
  | $func51263 | @ | 0aaeb74a:0x2466843
  | $func51313 | @ | 0aaeb74a:0x246c885
  | $func34708 | @ | 0aaeb74a:0x19938e1
  | $func1310 | @ | 0aaeb74a:0x4c7148
  | $func1212 | @ | 0aaeb74a:0x431bc4
  | $_Z14godot_web_mainiPPc | @ | 0aaeb74a:0x2cfd7e
  | __Z14godot_web_mainiPPc | @ | tmp_js_export.js:9
  | $__main_argc_argv | @ | 006438ee:0xa5975
  | callMain | @ | tmp_js_export.js:9
  | (anonymous) | @ | tmp_js_export.js:804
  | (anonymous) | @ | tmp_js_export.js:799
  | Promise.then |   |  
  | start | @ | tmp_js_export.js:778
  | (anonymous) | @ | tmp_js_export.js:837
  | Promise.then |   |  
  | startGame | @ | tmp_js_export.js:836
  | (anonymous) | @ | tmp_js_export.html:181
  | (anonymous)
```

I've tried using different entry point names using
```
struct SharedExtension;

#[gdextension(entry_symbol = gdext_shared_rust_init)]
unsafe impl ExtensionLibrary for SharedExtension {}
```

Which doesn't work. As soon as I remove the other extensions (so I leave `shared.gdextension`) it starts working again.

I use these Emscripten compile flags:
```
[target.wasm32-unknown-emscripten]
rustflags = [
"-C", "link-args=-sSIDE_MODULE=2",
"-C", "link-args=-pthread", # was -sUSE_PTHREADS=1 in earlier emscripten versions
"-C", "target-feature=+atomics,+bulk-memory,+mutable-globals",
"-Zlink-native-libraries=no",
"-Cllvm-args=-enable-emscripten-cxx-exceptions=0",
]
```

I also created two projects to recreate the issue:
[single-rust-project.zip](https://github.com/user-attachments/files/18115972/single-rust-project.zip)
[multiple-rust-project.zip](https://github.com/user-attachments/files/18115974/multiple-rust-project.zip)

I'm really eager to help this project move forward, and I would say I'm quite well-versed in WebAssembly, however I have no idea where to get started. I tried enabling `-sASSERTIONS` and `-sASSERTIONS=2` but this gives me a `resolved is not a function error` so no dice...

Any tips are very welcome, and if you need more information please let me know!

Thank you for the amazing work on this library, it's awesome!
Kind regards,