Add example pre-run instruction handler in EVM execution loop

[yascha]

Add example of (unsafe) implementation of a handler that can be used to execute arbitrary EVM calls before a given evm instruction. Useful in the new REVM model.

Example usage in EVM builder:

let old_handle = handler.execution_loop.pre_run_interpreter.clone();
            handler.execution_loop.pre_run_interpreter = Arc::new(
                move |evm: &mut Evm<'_, IE, DB>,
                      table: &[Box<dyn Fn(&mut Interpreter, &mut Evm<'_, IE, DB>)>; 256],
                      frame: &mut Box<CallStackFrame>|
                      -> Option<InterpreterAction> {
                    let engine_evm = EngineEVM {
                        evm,
                        table,
                        current_stack_frame: frame,
                    };
                    if let Some(pre_run) = IE::on_pre_run_interpreter(engine_evm) {
                        return Some(pre_run);
                    }
                    old_handle(evm, table, frame)
                },
            );

[rakita]

Ty, will check it out

[gakonst]

@yascha interesting, how do you think about the use case for this?

[yascha]

@gakonst with the old implementation of revm, it was very easy to manipulate the evm (in a very custom manner) via rust code. The new model has some incredibly nice changes, but it makes the evm manipulation trickier.
I've been using a variant of this hook for some time to enable executing arbitrary evm code anywhere within a callstack.

[rakita]

Effort is moved to this PR: #1369