RBParser is able (and tested) to produce AST with error nodes and precise error and warning information (notices)

The handling of error with error blocks or syntax error notifications is inferior because they are activated too early, without so much context: there is no AST yet, so such errors are only identified with a message string and a single position.
Moreover, they add complexity to the Parser code.

This PR tries to do what #12912 could not: remove errorBlock from RBParser.
What changed since then is a lot a cleanup and the RBNotice API, so I hope this will work now.

Features

• no more beFaulty, errorBlock or even SyntaxErrorNotification: the parser only goal is to generate AST, not to care about your feeling or water down bad news. You ask an AST, you get an AST, no questions asked, not many flavors to choose.
• new method RBProgramNode>>checkFaulty: that simulates the old parser handling of error.
  Therefore, clients that rely on beFaulty, errorBlock and/or SyntaxErrorNotification: can just use this method on the resulting AST and should get the same behavior.
  Note that the receiver is an AST node, not a parser, this is neat.
• Method on the class side of RBParser parse(Faulty)?(Expression|Method):(onError:)? are still here, and use checkFaulty: to achieve the same results but in a smoother way.