Test lexer output (tokens)

[ris58h]

We can test a parser output via *.tree files but it's not possible yet to test a lexer output.

[agoss94]

I created some code for testing antlr parsers and lexers that would be able to handle this Antlr testing with Airbag.

I could see the functionality being applied here as you could jusst dump the tokens in whatever format you like and use them as expected use case for comparing with the actual lexer output. I am now looking for feedback on my code and would like to incorporate it in some form into the antlr ecosystem.