allow --login to be used with nu's --commands parameter (#10253)

# Description

This PR allows the `--login`/`-l` parameter to be used with nushell's
`--commands`/`-c` parameter. When you do this, since you're invoking it
with the `-l` flag, nushell will load your env.nu, config.nu, and
login.nu, in that order. Then it will proceed to run your commands. I
think this provides a better quality of life when you want to run
scripts with your personal config files as a login shell.


### Before (these entries are from the default_env.nu)

![image](https://github.com/nushell/nushell/assets/343840/ce7adcd0-419e-485c-b7d1-f11f162e8e9e)


### After (these entries are from my personal env.nu)

![image](https://github.com/nushell/nushell/assets/343840/33bbc06b-983c-4461-8274-290e4c712506)


closes https://github.com/nushell/nushell/issues/9833

# User-Facing Changes
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helps us keep track of breaking changes. -->

# Tests + Formatting
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- `cargo fmt --all -- --check` to check standard code formatting (`cargo
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> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After Submitting
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src/run.rs

@@ -35,6 +35,7 @@ pub(crate) fn run_commands(
             parsed_nu_cli_args.plugin_file,
             NUSHELL_FOLDER,
         );
+
         perf(
             "read plugins",
             start_time,
@@ -45,8 +46,8 @@ pub(crate) fn run_commands(
         );
 
         let start_time = std::time::Instant::now();
-        // only want to load config and env if relative argument is provided.
-        if parsed_nu_cli_args.env_file.is_some() {
+        // If we have a env file parameter *OR* we have a login shell parameter, read the env file
+        if parsed_nu_cli_args.env_file.is_some() || parsed_nu_cli_args.login_shell.is_some() {
             config_files::read_config_file(
                 engine_state,
                 &mut stack,
@@ -56,6 +57,7 @@ pub(crate) fn run_commands(
         } else {
             config_files::read_default_env_file(engine_state, &mut stack)
         }
+
         perf(
             "read env.nu",
             start_time,
@@ -66,7 +68,8 @@ pub(crate) fn run_commands(
         );
 
         let start_time = std::time::Instant::now();
-        if parsed_nu_cli_args.config_file.is_some() {
+        // If we have a config file parameter *OR* we have a login shell parameter, read the config file
+        if parsed_nu_cli_args.config_file.is_some() || parsed_nu_cli_args.login_shell.is_some() {
             config_files::read_config_file(
                 engine_state,
                 &mut stack,
@@ -74,6 +77,7 @@ pub(crate) fn run_commands(
                 false,
             );
         }
+
         perf(
             "read config.nu",
             start_time,
@@ -82,6 +86,21 @@ pub(crate) fn run_commands(
             column!(),
             use_color,
         );
+
+        // If we have a login shell parameter, read the login file
+        let start_time = std::time::Instant::now();
+        if parsed_nu_cli_args.login_shell.is_some() {
+            config_files::read_loginshell_file(engine_state, &mut stack);
+        }
+
+        perf(
+            "read login.nu",
+            start_time,
+            file!(),
+            line!(),
+            column!(),
+            use_color,
+        );
     }
 
     // Before running commands, set up the startup time