Allow underscores in integers and floats (#7759)

# Description

This PR makes changes that allow underscores in numbers.

Example:
```nu
# allows underscores to be placed arbitrarily to enhance readability.
let pi = 3.1415_9265_3589_793

# works with integers
let num = 1_000_000_000_000
let fav_color = 0x68_9d_6a
```

crates/nu-parser/tests/test_parser.rs

@@ -64,6 +64,29 @@ pub fn parse_int() {
     ))
 }
 
+#[test]
+pub fn parse_int_with_underscores() {
+    let engine_state = EngineState::new();
+    let mut working_set = StateWorkingSet::new(&engine_state);
+
+    let (block, err) = parse(&mut working_set, None, b"420_69_2023", true, &[]);
+
+    assert!(err.is_none());
+    assert_eq!(block.len(), 1);
+    let expressions = &block[0];
+    assert_eq!(expressions.len(), 1);
+    assert!(matches!(
+        expressions[0],
+        PipelineElement::Expression(
+            _,
+            Expression {
+                expr: Expr::Int(420692023),
+                ..
+            }
+        )
+    ))
+}
+
 #[test]
 pub fn parse_binary_with_hex_format() {
     let engine_state = EngineState::new();