Add builtin ByteArray type

[paulcadman]

This PR adds support for a builtin ByteArray type and associated functions for constructing a ByteArray from a list of bytes and a function to query the size of the ByteArray. It is only available in the Anoma backend.

In Core / Tree, ByteArray constant is stored using a Haskell ByteString.

In Anoma the ByteArray is stored as a cell where the head is the length of the ByteArray and the tail is an integer is an integer formed by concatenating the bytes in the array using little-endian byte ordering.

The Nock for constructing a ByteArray uses the length, add, folder and lsh functions from the Anoma hoon stdlib. See the code comment for more details.

Example:

module test082;

import Stdlib.Prelude open;
import Stdlib.Debug.Trace open;

builtin bytearray
axiom ByteArray : Type;

builtin bytearray-from-list-byte
axiom mkByteArray : List Byte -> ByteArray;

builtin bytearray-size
axiom size : ByteArray -> Nat;

bs0 : ByteArray := mkByteArray [];

bs1 : ByteArray := mkByteArray [0x0; 0x0; 0x0];

bs2 : ByteArray := mkByteArray [0x1; 0x0; 0x0; 0x0];

bs3 : ByteArray := mkByteArray [0x2; 0x1];

bs4 : ByteArray := mkByteArray [0x100];

main : ByteArray :=
  trace (size bs0)
   >-> trace bs0
   >-> trace (size bs1)
    >-> trace bs1
    >-> trace (size bs2)
    >-> trace bs2
    >-> trace (size bs3)
    >-> trace bs3
    >-> trace (size bs4)
    >-> bs4;

Output using tests/Anoma/Compilation/positive/test082.juvix

$ juvix compile anoma -g test082.juvix
$ juvix dev nockma run test082.pretty.nockma
0
[0 0]
3
[3 0]
4
[4 1]
2
[2 258]
1
[1 0]