perlcritic: Clean up product_image_rotate.pl
perlcritic: Clean up product_image_rotate.pl

- Useless interpolation of literal string.  See page 51 of PBP.
- Regular expression without "/x" flag.  See page 236 of PBP
- Regular expression without "/m" flag.  See page 237 of PBP.
- Regular expression without "/s" flag.  See pages 240,241 of PBP.
- Unreachable code
- Postfix control "if" used.  See pages 93,94 of PBP.

Additional fixes
- Validate the angle parameter
- Return 400 if the parameters are not valid
- Return 404 if an image with the given $imgid does not exist
- Return 500 if normalization was requested but cannot be performed

openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server