[C++] Handle quoted field names during string schema parsing

The current implementation of Type::buildTypeFromString cannot handle string schemas with quoted field names. The following code will raise a logic error of "Unrecognized character.":

auto schema = Type::buildTypeFromString("struct<`quoted.field`:string>"); // Fails

Besides that, two other limitations have been encountered:

• Cannot parse a string schema that only has a timestamp with local time zone type in root.

  Type::buildTypeFromString("timestamp with local time zone"); // Fails
  

• It allows to create struct types without setting a field name, which (based on the Java implementation) should not be a valid ORC schema.

  Type::buildTypeFromString("struct<struct<bigint>>"); // Works