solidity-parser-antlr: rename `TypeString` to `ASTNodeTypeString`
solidity-parser-antlr: rename `TypeString` to `ASTNodeTypeString`

I think `ASTNodeTypeString` is a better name.
dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,borisyankov/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped