fix: preserve interface-specific export macros in wrapper generation

The wrapper generation was incorrectly removing ALL export macros with a
sed filter, including the interface-specific ones needed for multi-interface
components. This caused build failures when wit-bindgen generates separate
export macros for each interface in multi-interface worlds.

Changes:
- Remove sed filter that stripped all `pub use __export_.*_cabi` statements
- Preserve interface-specific export macros like __export_*_interface_*_cabi
- Allow main export macro to correctly reference interface-specific macros
- Enable multi-interface component builds with fixed wit-bindgen

This resolves build errors like:
  error[E0433]: failed to resolve: could not find `__export_*_interface_*_cabi`

The fix works with both single-interface and multi-interface components,
maintaining backward compatibility while enabling the export macro visibility
fix from wit-bindgen.

Author: avrabe

rust/rust_wasm_component_bindgen.bzl

@@ -60,9 +60,9 @@ pub mod wit_bindgen {
 """
 
     # Concatenate wrapper content with generated bindings
-    # Also remove duplicate 'pub use' statements that wit-bindgen might generate
+    # Keep interface-specific export macros but remove any duplicate top-level exports
     ctx.actions.run_shell(
-        command = '''echo '{}' > {} && echo "" >> {} && cat {} | sed 's/^pub use __export_.*_cabi;$//' >> {}'''.format(
+        command = '''echo '{}' > {} && echo "" >> {} && cat {} >> {}'''.format(
             wrapper_content.replace("'", "'\"'\"'"),
             out_file.path,
             out_file.path,