Initial support for an ANTLR-based Influx DB query parser

The initial grammar only understands these queries:
- list series
- select * from my_series
- select * from "312 _ strange\" name"

Two tests check queries which we expect can be parsed and cannot.

The ANTLR Maven plugin builds the lexer and parser during the
generate-sources phase.

This only a first step and the query is not ready to be merged. The goal is to be able the current regular expression based parser first. Later on (in another PR), we can expand the grammar to support more Influx language constructs.
Updated. Note that with the new MetricHandler paths, a tenant cannot be named "influx", otherwise it conflicts with the InfluxHandler base path.