Adding expect/actual implementation for openFileWithDefaultApplication

[N7ghtm4r3]

Hi @vinceglb!

Could be a way to avoid each time to create a custom expect/actual implementation to wrap the missing behavior of openFileWithDefaultApplication on the web target create an internal wrapper on commonMain with a onWeb arg to eventually perform an alternative action if invoked by a webapp?

For example:

openFileWithDefaultApplicationWrapper(
    onWeb: ((PlatformFile) -> Unit)? = null
)