builtin: add {de,}compress builtins

[pbardea]

demo@127.0.0.1:26257/movr> select compress('hello there', 'gzip');
                                                        compress
------------------------------------------------------------------------------------------------------------------------
  \037\213\010\000\000\000\000\000\000\377\312H\315\311\311W(\311H-J\005\004\000\000\377\377P\351\022m\013\000\000\000
(1 row)

demo@127.0.0.1:26257/movr> select decompress(compress('hello there', 'gzip'), 'gzip');
  decompress
---------------
  hello there
(1 row)

demo@127.0.0.1:26257/movr> select length(repeat('hi there', 100)::bytes);
  length
----------
     800
(1 row)

demo@127.0.0.1:26257/movr> select length(compress(repeat('hi there', 100)::bytes, 'gzip'));
  length
----------
      39
(1 row)

demo@127.0.0.1:26257/movr> select decompress('not compressed', 'gzip');
ERROR: decompress(): failed to decompress: gzip: invalid header
demo@127.0.0.1:26257/movr> select decompress('bad codec', 'zip');
ERROR: decompress(): only 'gzip' codec is supported for decompress()
SQLSTATE: 22023

This commits adds builtins to compress and decompress bytes. The only
codec currently supported is gzip.

Release note (sql change): New builtins, compress(data, codec) and
decompress(data, codec), are added which can compress and decompress
bytes with the specified codec. Gzip is the only currently supported
codec.

[cockroach-teamcity]

This change is 

[dt]

naming bikeshed:
should we make it de/compress(bytes, codec) similar to encode(payload, format) in case we add more compression codecs?

[pbardea]

Good idea! Updated.

[pbardea]

TFTR
bors r+

[craig]

Build failed:

• GitHub CI (Cockroach)

[pbardea]

One more time.
bors r+

[craig]

Build succeeded:

• GitHub CI (Cockroach)