ensure that when nu evaluates files, it allows early returns (#7415)

# Description

Fixes #7301.

# User-Facing Changes

`return` can now be used in scripts without explicit `def main`.

# Tests + Formatting

Don't forget to add tests that cover your changes. (I'm not sure how to
test this.)

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-cli/src/eval_file.rs

@@ -106,13 +106,21 @@ pub fn evaluate_file(
             &file,
             file_path_str,
             PipelineData::empty(),
+            true,
         ) {
             std::process::exit(1);
         }
-        if !eval_source(engine_state, stack, args.as_bytes(), "<commandline>", input) {
+        if !eval_source(
+            engine_state,
+            stack,
+            args.as_bytes(),
+            "<commandline>",
+            input,
+            true,
+        ) {
             std::process::exit(1);
         }
-    } else if !eval_source(engine_state, stack, &file, file_path_str, input) {
+    } else if !eval_source(engine_state, stack, &file, file_path_str, input, true) {
         std::process::exit(1);
     }