Updated a couple of solutions to use newer ways to instantiate node buffers

[mpmckenna8]

Changed the solutions to a couple of the exercises to use the non-deprecated way to create node buffers. It is kind of confusing because you do still use like

const arr = new Uint16Array(20);

In a browser but in the node docs say to use Buffer.from(stufftomakebuffer) or Buffer.alloc(size) to make new buffers. Though using new Buffer should work for the for a while yet. Maybe both kinds of solutions should be shown because new Buffer() is used a lot?

see: https://nodejs.org/api/buffer.html#buffer_class_method_buffer_from_buffer