Enable Squiz.WhiteSpace.CastSpacing

Ensure cast statements don't contain whitespace:

 Valid:
  (int)$foo

 Invalid:
  ( int )$bar

Squiz.WhiteSpace.CastSpacing does it nicely:

 (int)$foo;
 -> valid

 ( int )$bar;
 -> Cast statements must not contain whitespace; expected \"(int)\"
    but found \"( int )\"

Change-Id: Ie986c370a22bf7c614e404cc381bc84f15368cf9