Add parser support for PostgreSQL's ENCODE() and DECODE() functions

[lukaseder]

In PostgreSQL, there are 2 functions called ENCODE() and DECODE():

• https://www.postgresql.org/docs/current/functions-binarystring.html

For example:

• encode ( bytes bytea, format text ) → text
• decode ( string text, format text ) → bytea

We should support parsing these with hard-coded format recognition. These 2 could be recognised:

• 'hex'
• 'base64'

Specifically the latter would be worth supporting in jOOQ in general.