Done as part of flattening the `util` module.
We have a function in `util::misc` that operates on scripts, it is an
implementation of `FindAndDelete` from Bitcoin Core and is primarily
useful for supporting `CODESEPARATOR`, which we do not support.
Move the public `script_find_and_remove` function out of `util/misc.rs` and into
`util/mod.rs`, delete the testing and deprecate the function.