* update docs for `@byteSwap`.
 * fix hash & eql functions for ZigLLVMFnIdBswap not updated to
   include vector len. this was causing incorrect bswap function
   being called in unrelated code
 * fix `@byteSwap` behavior tests only testing comptime and not
   runtime operations
 * implement runtime `@byteSwap`
 * fix incorrect logic in ir_render_vector_to_array and
   ir_render_array_to_vector with regards to whether or not to bitcast
 * `@byteSwap` accepts an array operand which it will cast to vector
 * simplify `@byteSwap` semantic analysis code and various fixes