Only collect module maps that are files.
Only collect module maps that are files.

`SwiftInfo` allows module maps to be passed as `File` or `string` (the latter to support paths of system modules in Xcode SDKs), so filter out any elements that aren't `File`s.

PiperOrigin-RevId: 357989635
(cherry picked from commit 0e4a897ad83bb18ff52c790d4cf619c4c585a7a6)

bazelbuild/tulsi,bazelbuild/tulsi,bazelbuild/tulsi,bazelbuild/tulsi,bazelbuild/tulsi,bazelbuild/tulsi