`abi_decode` requires too many proxy arguments

The `abi_decode` definition in `std.solc`: https://github.com/argotorg/solcore/blob/73e0ccd3325de0f7baa10d96bcd3e04d4f892db9/std/std.solc#L594 currently requires a proxy parameter for the type of `reader` (i.e. whether we're decoding from calldata or memory). This is required as monomorphization will otherwise fail due to ambiguity (as `reader` would otherwise appear only in the constraints and not in the function signature).

This means that we are currently unable to implement the `abi.decode` from classic solidity which can generically decode from both memory and calldata:

```
// SPDX-License-Identifier: AGPL-3.0
pragma solidity 0.8.28;

contract SolidityCalldataAccess {
function abi_mem(bytes memory data) external pure returns (uint) {
return abi.decode(data, (uint));
}

function abi_cd(bytes calldata data) external pure returns (uint) {
return abi.decode(data, (uint));
}
}
```

Start at std/std.solc line 594 and inspect how abi_decode exposes the reader type and how monomorphization handles its constraints. Reproduce the issue with the SolidityCalldataAccess example from the report; done means abi.decode can generically handle both memory and calldata without requiring the extra proxy argument.

Written by the indexing model from the issue text.