add wrapper around our custom binding to replace unsupported parameters

[psteinroe]

now that we have a custom lexer, we can simply build a preprocessor for libpg_query to replace unsupported tokens with supported parameters ($0, $1, …)

also ensure that we support all of the below in the lexer.

list of parameters to support (incomplete):

• :'name'
• @name (sqlc)

more here: #396