Replace antlr4 deps with antlr4-runtime #454
Description
The ANTLR used in the parser is a very large and heavy library, taking up around 50MB when unjarred.
This makes it difficult to use Lacinia easily with AWS Lambda, etc.
Therefore, I propose to replace ANTLR with the antlr4-runtime dependency rather than the whole thing. To do this, clj-antlr needs to be removed and pre-generated java code should be interop-ed instead.