add start_time to ps -l on macos (#14127)

# Description

This PR adds `start_time` to the MacOS `ps -l` command. Was requested in
discord. `start_time` is displayed in `Local` time.


![image](https://github.com/user-attachments/assets/b3743cde-af43-4756-9e2a-54689104fb25)


# User-Facing Changes
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/cc @cablehead

crates/nu-command/src/system/ps.rs

@@ -1,3 +1,5 @@
+#[cfg(target_os = "macos")]
+use chrono::{Local, TimeZone};
 #[cfg(windows)]
 use itertools::Itertools;
 use nu_engine::command_prelude::*;
@@ -175,6 +177,10 @@ fn run_ps(
             #[cfg(target_os = "macos")]
             {
                 record.push("cwd", Value::string(proc.cwd(), span));
+                let timestamp = Local
+                    .timestamp_nanos(proc.start_time * 1_000_000_000)
+                    .into();
+                record.push("start_time", Value::date(timestamp, span));
             }
         }
 

crates/nu-system/src/macos.rs

@@ -25,6 +25,7 @@ pub struct ProcessInfo {
     pub curr_res: Option<RUsageInfoV2>,
     pub prev_res: Option<RUsageInfoV2>,
     pub interval: Duration,
+    pub start_time: i64,
 }
 
 pub fn collect_proc(interval: Duration, _with_thread: bool) -> Vec<ProcessInfo> {
@@ -94,6 +95,7 @@ pub fn collect_proc(interval: Duration, _with_thread: bool) -> Vec<ProcessInfo>
         let curr_time = Instant::now();
         let interval = curr_time.saturating_duration_since(prev_time);
         let ppid = curr_task.pbsd.pbi_ppid as i32;
+        let start_time = curr_task.pbsd.pbi_start_tvsec as i64;
 
         let proc = ProcessInfo {
             pid,
@@ -107,6 +109,7 @@ pub fn collect_proc(interval: Duration, _with_thread: bool) -> Vec<ProcessInfo>
             curr_res,
             prev_res,
             interval,
+            start_time,
         };
 
         ret.push(proc);