chore(visitor): break up visitor to multiple modules (#9306)

### Description

This is a prefactor to break up `visitor.rs` into multiple files. This
is primarily just moving code around, but there are a few more in depth
changes:
-
2873556
changes `TaskWarning` to only be constructed if there are missing envs,
removing the need to check later on
-
88e98c5
changes so we no longer call `which` for every task to find the package
manager binary. We instead call this on construction, but will only
handle the error case on actual command creation.

I highly recommend reviewing each commit on it's own. All commits that
move code do only that so hopefully that makes it easier to review.

### Testing Instructions

Integration tests and some basic manual testing.

crates/turborepo-lib/src/opts.rs

@@ -170,15 +170,32 @@ pub struct RunOpts {
     pub ui_mode: UIMode,
 }
 
+/// Projection of `RunOpts` that only includes information necessary to compute
+/// pass through args.
+#[derive(Debug)]
+pub struct TaskArgs<'a> {
+    pass_through_args: &'a [String],
+    tasks: &'a [String],
+}
+
 impl RunOpts {
-    pub fn args_for_task(&self, task_id: &TaskId) -> Option<Vec<String>> {
+    pub fn task_args(&self) -> TaskArgs {
+        TaskArgs {
+            pass_through_args: &self.pass_through_args,
+            tasks: &self.tasks,
+        }
+    }
+}
+
+impl<'a> TaskArgs<'a> {
+    pub fn args_for_task(&self, task_id: &TaskId) -> Option<&'a [String]> {
         if !self.pass_through_args.is_empty()
             && self
                 .tasks
                 .iter()
                 .any(|task| task.as_str() == task_id.task())
         {
-            Some(self.pass_through_args.clone())
+            Some(self.pass_through_args)
         } else {
             None
         }

crates/turborepo-lib/src/process/command.rs

@@ -9,6 +9,7 @@ use turbopath::AbsoluteSystemPathBuf;
 
 /// A command builder that can be used to build both regular
 /// child processes and ones spawned hooked up to a PTY
+#[derive(Debug, Clone)]
 pub struct Command {
     program: OsString,
     args: Vec<OsString>,

crates/turborepo-lib/src/run/mod.rs

@@ -448,7 +448,6 @@ impl Run {
             package_inputs_hashes,
             &self.env_at_execution_start,
             &global_hash,
-            self.opts.run_opts.env_mode,
             self.color_config,
             self.processes.clone(),
             &self.repo_root,