Use `main` entrypoint for note scripts

I compiled this P2ID note script using the `main` entrypoint:

```rust
#![no_std]
#![no_main]

#[global_allocator]
static ALLOC: miden::BumpAlloc = miden::BumpAlloc::new();

#[panic_handler]
fn my_panic(_info: &core::panic::PanicInfo) -> ! {
loop {}
}

mod bindings;

fn main() {
let inputs = miden::note::get_inputs();
let target_account_id_felt = inputs[0];
let account_id = miden::account::get_id();
assert_eq!(account_id.as_felt(), target_account_id_felt);
let assets = miden::note::get_assets();
for asset in assets {
bindings::miden::basic_wallet::basic_wallet::receive_asset(asset);
}
}

#[no_mangle]
fn __main_void() -> i32 {
main();
0
}

#[no_mangle]
fn __wasm_call_dtors() {}

#[no_mangle]
fn __wasi_proc_exit(_: u32) {}
```

`__*` Rust functions need to be defined to make component encoder happy. Otherwise, it will fail on unknown imports. I presume they are only implemented in `std` environment. The command component is heavy on `wasi:*` code for I/O, files, etc. so I believe `no_std` is not really supported for the command components. We can "hide" those functions in the Miden SDK crate or generate via macros.

The Rust code above compiles to the following Wasm component - https://gist.github.com/greenhat/5ea1e3c0651f717137f778d958b5cbd3

There are two problems with this component:

1. The second core module (`core module (;1;)`) with all `wasi:*` machinery is brought in by the adapter in `cargo-component` at https://github.com/bytecodealliance/cargo-component/blob/37c042e3340c25cfcb3646a2445e46321289bbfe/src/lib.rs#L900-L902 and is built from https://github.com/bytecodealliance/wasmtime/blob/b9874992ba92b06cbbfab7131ef740ba4c10720f/crates/wasi-preview1-component-adapter/src/lib.rs# crate in `wasmtime` repo.
I want to craft our own some sort of "empty" adapter to get rid of the `wasi:*` code.

2. The `_start` function is supposed to be the entrypoint for the command component (used in the second core module):
```wasm
(func $_start (;6;) (type 5)
(local i32)
block ;; label = @1
block ;; label = @2
global.get $GOT.data.internal.__memory_base
i32.const 1048612
i32.add
i32.load
br_if 0 (;@2;)
global.get $GOT.data.internal.__memory_base
i32.const 1048612
i32.add
i32.const 1
i32.store
call $__wasm_call_ctors
call $__main_void
local.set 0
call $__wasm_call_dtors
local.get 0
br_if 1 (;@1;)
return
end
unreachable
unreachable
end
local.get 0
call $__wasi_proc_exit
unreachable
)
```

The Rust code for it is in the `wasi-libc` - https://github.com/WebAssembly/wasi-libc/blob/98897e29fcfc81e2b12e487e4154ac99188330c4/libc-bottom-half/crt/crt1-command.c

With `__wasm_call_ctors` and `__wasm_call_dtors` being empty functions, the only thing that this code is doing is preventing the reentrance of the `_start` function.
We can probably ignore `_start` altogether and call the `__main_void` function directly as our entrypoint.