Add and use new Signals struct (#13314)

# Description
This PR introduces a new `Signals` struct to replace our adhoc passing
around of `ctrlc: Option<Arc<AtomicBool>>`. Doing so has a few benefits:
- We can better enforce when/where resetting or triggering an interrupt
is allowed.
- Consolidates `nu_utils::ctrl_c::was_pressed` and other ad-hoc
re-implementations into a single place: `Signals::check`.
- This allows us to add other types of signals later if we want. E.g.,
exiting or suspension.
- Similarly, we can more easily change the underlying implementation if
we need to in the future.
- Places that used to have a `ctrlc` of `None` now use
`Signals::empty()`, so we can double check these usages for correctness
in the future.

crates/nu-cli/src/commands/history/history_.rs

@@ -47,7 +47,7 @@ impl Command for History {
         if let Some(config_path) = nu_path::config_dir() {
             let clear = call.has_flag(engine_state, stack, "clear")?;
             let long = call.has_flag(engine_state, stack, "long")?;
-            let ctrlc = engine_state.ctrlc.clone();
+            let signals = engine_state.signals().clone();
 
             let mut history_path = config_path;
             history_path.push("nushell");
@@ -107,7 +107,7 @@ impl Command for History {
                             file: history_path.display().to_string(),
                             span: head,
                         })?
-                        .into_pipeline_data(head, ctrlc)),
+                        .into_pipeline_data(head, signals)),
                     HistoryFileFormat::Sqlite => Ok(history_reader
                         .and_then(|h| {
                             h.search(SearchQuery::everything(SearchDirection::Forward, None))
@@ -122,7 +122,7 @@ impl Command for History {
                             file: history_path.display().to_string(),
                             span: head,
                         })?
-                        .into_pipeline_data(head, ctrlc)),
+                        .into_pipeline_data(head, signals)),
                 }
             }
         } else {

crates/nu-cli/src/nu_highlight.rs

@@ -32,7 +32,7 @@ impl Command for NuHighlight {
     ) -> Result<PipelineData, ShellError> {
         let head = call.head;
 
-        let ctrlc = engine_state.ctrlc.clone();
+        let signals = engine_state.signals();
         let engine_state = std::sync::Arc::new(engine_state.clone());
         let config = engine_state.get_config().clone();
 
@@ -50,7 +50,7 @@ impl Command for NuHighlight {
                 }
                 Err(err) => Value::error(err, head),
             },
-            ctrlc,
+            signals,
         )
     }
 

crates/nu-cli/src/repl.rs

@@ -43,7 +43,7 @@ use std::{
     io::{self, IsTerminal, Write},
     panic::{catch_unwind, AssertUnwindSafe},
     path::{Path, PathBuf},
-    sync::{atomic::Ordering, Arc},
+    sync::Arc,
     time::{Duration, Instant},
 };
 use sysinfo::System;
@@ -271,11 +271,8 @@ fn loop_iteration(ctx: LoopContext) -> (bool, Stack, Reedline) {
     perf!("merge env", start_time, use_color);
 
     start_time = std::time::Instant::now();
-    // Reset the ctrl-c handler
-    if let Some(ctrlc) = &mut engine_state.ctrlc {
-        ctrlc.store(false, Ordering::SeqCst);
-    }
-    perf!("reset ctrlc", start_time, use_color);
+    engine_state.reset_signals();
+    perf!("reset signals", start_time, use_color);
 
     start_time = std::time::Instant::now();
     // Right before we start our prompt and take input from the user,