Type checker updates and bug fixes (#57)

* Add new ast extractor for type checker

* Remove old ast extractor and add new types

* Remove old ast types

* Rename astExtractor.ts to extractor.ts

* Rename javaSpecTypes.ts to specificationTypes.ts

* Fix import bug

* Add types for compilation unit to type checker ast extractor

* Rename type checker ast extractor specification imports

* Add typing into type checker ast extractor

* Change typechecker to use new AST

* Rename type checker errors label

* Add type interface

* Fix binary, unary and postfix type checking

* Add support for swtich statements

* Add support for do statements

* Add support for try catch statements

* Add support for throw statements

* Add location to type check error in return statement

* Add location to 2 typechecker errors that is missing location

* Refactor types system in type checker

* Sort imports in prechecks.ts

Author: bryanlohxz