Move Value to helpers, separate span call (#10121)

# Description

As part of the refactor to split spans off of Value, this moves to using
helper functions to create values, and using `.span()` instead of
matching span out of Value directly.

Hoping to get a few more helping hands to finish this, as there are a
lot of commands to update :)

# User-Facing Changes
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# Tests + Formatting
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---------

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>
Co-authored-by: WindSoilder <windsoilder@outlook.com>

crates/nu-cli/tests/support/completions_helpers.rs

@@ -40,33 +40,30 @@ pub fn new_engine() -> (PathBuf, String, EngineState, Stack) {
     // Add pwd as env var
     stack.add_env_var(
         "PWD".to_string(),
-        Value::String {
-            val: dir_str.clone(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(dir_str.clone(), nu_protocol::Span::new(0, dir_str.len())),
     );
     stack.add_env_var(
         "TEST".to_string(),
-        Value::String {
-            val: "NUSHELL".to_string(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(
+            "NUSHELL".to_string(),
+            nu_protocol::Span::new(0, dir_str.len()),
+        ),
     );
     #[cfg(windows)]
     stack.add_env_var(
         "Path".to_string(),
-        Value::String {
-            val: "c:\\some\\path;c:\\some\\other\\path".to_string(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(
+            "c:\\some\\path;c:\\some\\other\\path".to_string(),
+            nu_protocol::Span::new(0, dir_str.len()),
+        ),
     );
     #[cfg(not(windows))]
     stack.add_env_var(
         "PATH".to_string(),
-        Value::String {
-            val: "/some/path:/some/other/path".to_string(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(
+            "/some/path:/some/other/path".to_string(),
+            nu_protocol::Span::new(0, dir_str.len()),
+        ),
     );
 
     // Merge environment into the permanent state
@@ -95,17 +92,14 @@ pub fn new_quote_engine() -> (PathBuf, String, EngineState, Stack) {
     // Add pwd as env var
     stack.add_env_var(
         "PWD".to_string(),
-        Value::String {
-            val: dir_str.clone(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(dir_str.clone(), nu_protocol::Span::new(0, dir_str.len())),
     );
     stack.add_env_var(
         "TEST".to_string(),
-        Value::String {
-            val: "NUSHELL".to_string(),
-            span: nu_protocol::Span::new(0, dir_str.len()),
-        },
+        Value::string(
+            "NUSHELL".to_string(),
+            nu_protocol::Span::new(0, dir_str.len()),
+        ),
     );
 
     // Merge environment into the permanent state
@@ -168,12 +162,7 @@ pub fn merge_input(
         engine_state,
         stack,
         &block,
-        PipelineData::Value(
-            Value::Nothing {
-                span: Span::unknown(),
-            },
-            None
-        ),
+        PipelineData::Value(Value::nothing(Span::unknown(),), None),
         false,
         false
     )