Eliminate unnecessary vector mask conversion during VectorUnbox for floating point VectorMask

Normally, the "VectorUnbox (VectorBox v)" can be optimized to "v" if their types are equal. And when unboxing vector mask, if their bottom_type is not equal, the VectorUnbox/VectorBox can also be eliminated by applying "VectorUnbox (VectorBox vmask) ==> VectorLoadMask (VectorStoreMask vmask)".

However, since some Vector APIs define different element type for floating point VectorMask (i.e. the logical APIs and "maskAll" use "long/int" as the element type, while others use "double/float"), the vector box/unbox types can be different for "VectorUnbox (VectorBox vmask)". The compiler will optimize it to "VectorLoadMask (VectorStoreMask vmask)". This is unnecessary and it can be optimized to "vmask", since double/float and long/int is the same for VectorMask.