Move step running into enum for dynamic ordering (#1188)

Co-authored-by: Stuart Reilly <sreilly@scottlogic.com>

src/runner.rs

@@ -2,8 +2,9 @@ use crate::ctrlc;
 use crate::error::{DryRun, SkipStep};
 use crate::execution_context::ExecutionContext;
 use crate::report::{Report, StepResult};
+use crate::step::Step;
 use crate::terminal::print_error;
-use crate::{config::Step, terminal::should_retry};
+use crate::terminal::should_retry;
 use color_eyre::eyre::Result;
 use std::borrow::Cow;
 use std::fmt::Debug;