Reduced LOC by replacing several instances of Value::Int {}, Value::Float{}, Value::Bool {}, and Value::String {} with Value::int(), Value::float(), Value::boolean() and Value::string() (#7412)

# Description

While perusing Value.rs, I noticed the `Value::int()`, `Value::float()`,
`Value::boolean()` and `Value::string()` constructors, which seem
designed to make it easier to construct various Values, but which aren't
used often at all in the codebase. So, using a few find-replaces
regexes, I increased their usage. This reduces overall LOC because
structures like this:
```
Value::Int {
  val: a,
  span: head
}
```
are changed into
```
Value::int(a, head)
```
and are respected as such by the project's formatter.
There are little readability concerns because the second argument to all
of these is `span`, and it's almost always extremely obvious which is
the span at every callsite.

# User-Facing Changes

None.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/env/load_env.rs

@@ -46,13 +46,7 @@ impl Command for LoadEnv {
                         let cwd = current_dir(engine_state, stack)?;
                         let rhs = rhs.as_string()?;
                         let rhs = nu_path::expand_path_with(rhs, cwd);
-                        stack.add_env_var(
-                            env_var,
-                            Value::String {
-                                val: rhs.to_string_lossy().to_string(),
-                                span: call.head,
-                            },
-                        );
+                        stack.add_env_var(env_var, Value::string(rhs.to_string_lossy(), call.head));
                     } else {
                         stack.add_env_var(env_var, rhs);
                     }
@@ -72,10 +66,7 @@ impl Command for LoadEnv {
                             let rhs = nu_path::expand_path_with(rhs, cwd);
                             stack.add_env_var(
                                 env_var,
-                                Value::String {
-                                    val: rhs.to_string_lossy().to_string(),
-                                    span: call.head,
-                                },
+                                Value::string(rhs.to_string_lossy(), call.head),
                             );
                         } else {
                             stack.add_env_var(env_var, rhs);

crates/nu-command/src/env/source_env.rs

@@ -53,10 +53,7 @@ impl Command for SourceEnv {
         };
         parent.pop();
 
-        let file_pwd = Value::String {
-            val: parent.to_string_lossy().to_string(),
-            span: call.head,
-        };
+        let file_pwd = Value::string(parent.to_string_lossy(), call.head);
 
         caller_stack.add_env_var("FILE_PWD".to_string(), file_pwd);