Support for MultilineStrings

GHC 9.12 introduces `MultilineStrings`, https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/multiline_strings.html which allows a string started (and endeded) with `""""` to span on multiples lines, such as: ```haskell str = """ hello world """ ``` Right now, it completely breaks the parser:  ``` (haskell ; [0, 0] - [4, 0] (ERROR ; [0, 0] - [3, 6] (bind ; [0, 0] - [3, 5] name: (variable) ; [0, 0] - [0, 3] match: (match ; [0, 4] - [3, 5] expression: (apply ; [0, 6] - [3, 5] function: (apply ; [0, 6] - [2, 8] function: (apply ; [0, 6] - [1, 8] function: (literal ; [0, 6] - [0, 8] (string)) ; [0, 6] - [0, 8] (ERROR ; [0, 8] - [0, 9] (ERROR)) ; [0, 8] - [0, 9] argument: (variable)) ; [1, 3] - [1, 8] argument: (variable)) ; [2, 3] - [2, 8] argument: (literal ; [3, 3] - [3, 5] (string))))) ; [3, 3] - [3, 5] (ERROR))) ; [3, 5] - [3, 6] ```