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

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

list of parameters to support (incomplete):

• :'name'
• @name (sqlc)

the preprocessor should also be usable by the type checker.

more here: #396