New file extensions and samples for SQL

This pull request adds 4 new extensions for SQL as requested here: #1099.
It doesn't add any new conflict on the extensions.
I also added a few samples (one per file extension) for SQL.

Examples of usages on GitHub:
- .prc - https://github.com/search?q=extension%3Aprc+create&type=Code&ref=searchresults
- .tab - https://github.com/search?q=extension%3Atab+create&type=Code&ref=searchresults
- .udf - https://github.com/search?q=extension%3Audf+create&type=Code&ref=searchresults
- .viw - https://github.com/search?q=extension%3Aviw+select&type=Code&ref=searchresults

I couldn't find many examples for .tab so I'm not sure we should add it.
I pushed it for the moment because it doesn't harm anything (no conflict).

I didn't push the regenerated ```samples.json``` because it had a lot of modifications which have nothing to do with this. However, I tested with it too and it works well.