fix(esm-lib): address review - rename is_entry_chunk, tighten REQUIRE_SCOPE guard
- Rename `is_entry_chunk` to `is_pure_runtime_chunk` and flip the
condition so the export guard reads positively: only pure runtime
chunks export `__webpack_require__`.
- Replace the blanket `needs_require` flag with a REQUIRE_SCOPE_GLOBALS
intersection check (same logic the runtime plugin uses in
handle_scope_globals). This ensures REQUIRE_SCOPE is only added when
the chunk actually contains globals that live on the __webpack_require__
object, rather than for any non-empty requirement set.