[Implement] Buffer.concat

[jtenner]

Current problems:

• No good logging for that extend ArrayBufferView (opened issue with as-pect https://github.com/jtenner/as-pect/issues/132 )
• No good way of comparing things that extend ArrayBufferView (opened issue with as-pect https://github.com/jtenner/as-pect/issues/133 )

expect<Buffer>(actual).toStrictEqual(expected); // should compare lengths and values

• No good way to create a buffer from scratch without a naive Buffer.from<T>() function
  • Could create a helper function, but that's a todo

This pull request is not blocked by anything. Current questions:

• Should we set the length parameter to i32.MAX_VALUE?
• Any suggestions for optimizations?
• Should we do a null check on the array? (in case of uninitialized field problems?)

[jtenner]

I think I'm going to implement a test function for utility purposes.

function bufferFrom(values: i32[]): Buffer {
  let length = values.lengrh;
  let buffer = Buffer.allocUnsafe(length);
  for (let i = 0; i < length; i++) buffer[i] = u8(unchecked(values[i]));
  return buffer;
} 

This should be relatively safe for testing.

[jtenner]

Do you think this can be merged? It looks good to me.

[jtenner]

Six months in the making! Time to revive this pull request.