Refactor SValBuilder::evalCast function. Make the function clear and get rid of redundant and repetitive code. Unite SValBuilder::evalCast, SimpleSValBuilder::dispatchCast, SimpleSValBuilder::evalCastFromNonLoc and SimpleSValBuilder::evalCastFromLoc functions into single SValBuilder::evalCast.
P.S. Inspired by D89055.
Now I'm going to make unittests for SValBuilder::evalCast. Let me ask you to offer me some examples of casts to check. As many cases we can collect as robust the test would be. E.g.
int x; // case 1 float y; x = y; int x; // case 2 (void)x; ...