[NFCI] Refactor types.hpp and separate sycl::vec into a header of its own (#13544)

This PR splits types.hpp to separate out `sycl::vec` into a new header,
vector.hpp. The PR also rearranges the code to group together
`sycl::vec` class and its helper functions; similarly for `SwizzleOp`
class and its helper functions.

Author: uditagarwal97