[Twig translation bridge] Improve error reporting of twig markup problems

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Indicate which file was being parsed if an exception is thrown while running translation:debug

When running the translation:debug command, if a template contains invalid twig markup,
an exception is thrown. This patch rethrows a new exception that includes the filename
being parsed in the message to aid debuging.
No, thanks, you're right. I thought more general was better, but, the problem is more that Twig_Error can't work out what file the error was in as there's no Template instance in the stack. I've updated to set the filename and re-throw the original. Think that's a better fix?