Graql Autocomplete library based on ANTLR

[haikalpribadi]

We need to implement an autocompletion tool to be used by an editor or console, that takes the ANTLR grammar into consideration, rather than string completion of a word. This has been done before, and we can research the best ways to do it. Here's a good start to look at a complete example: https://tomassetti.me/autocompletion-editor-antlr

[flyingsilverfin]

In the future console, we will want an autocomplete based on PEST. cc @alexjpwalker @dmitrii-ubskii