Add a `swift_explicit_module` output group to the `swift_clang_module_aspect` to provide a way to invoke the aspect from the command line and retrieve the `.pcm` file.
Add a `swift_explicit_module` output group to the `swift_clang_module_aspect` to provide a way to invoke the aspect from the command line and retrieve the `.pcm` file.

This provides an easier way to manually verify that a `{cc,objc}_library` builds correctly as an explicit module.

PiperOrigin-RevId: 353103538
(cherry picked from commit 1b63232f01d665aab1157a4d66a4ee2c91c2e9a6)

bazelbuild/rules_swift,bazelbuild/rules_swift