[Feature]: Update All fn Selector "Magic Values" Into Explicit fn Selector Calculation

[0xNeshi]

What is the feature you would like to see?

Example

Turn this:

 const SINGLE_TRANSFER_FN_SELECTOR: FixedBytes<4> = fixed_bytes!("f23a6e61");

Into this:

const SINGLE_TRANSFER_FN_SELECTOR: [u8; 4] = function_selector!(
    "onERC1155Received",
    Address,
    Address,
    U256,
    U256,
    Bytes
);

Original comment that prompted this issue's creation: #417

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