Isolating refinement type checker from java syntax tree traversing

[FrogOfJuly]

My idea is to separate typing rules to stateless external class.

• It will unbind typing from traversing java syntax tree.
• It will make adding new typing rules easier.
• It will bring Liquid Java implementation closer to its formalization.

I do not know if it is possible or useful, so I am creating this pull request to discuss.

[FrogOfJuly]

Also, it seems relevant to split the context into global and local to match formalization