chore(builtin/cast): cleanup

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(kernel/pos_info_provider): add support for file names in pos_info_provider

The idea is to include the file name when displaying justification objects.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(kernel/pos_info_provider): add support for file names in pos_info_provider