Implement Java Version of this Plugin's Logic and Benchmark against Current Version

[original-brownbear]

It's in the title, also see #111 (comment) for the background.

[suyograo]

Just as an FYI when we get to this. The original ruby (and C!) implementation from @jordansissel is here https://github.com/jordansissel/ruby-grok. We should port all the awesome tests from that library (even if it's in Ruby). Also, for reference, there is a ingest node implementation of grok from @talevy https://github.com/elastic/elasticsearch/blob/master/modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/Grok.java.

Ideally, we would have a Grok library we can reuse in both ES and LS, but for now, we can have the Java implementation embedded here. Open to separating this as well from the get go. We can discuss.

[jordansissel]

The grok implementation in Ingest won't work for Logstash because:

• it combines patterns with regexp union | which prevents break_on_match => false from working in Logstash gork.
• cannot be extracted from Elasticsearch due to dependency on Elasticsearch.

I'm open to review any implementation details or to share history on grok (originally written in 2004!), if you need it.

+1 on exploring this moving to java.

My intuition is that moving the capture mapping to Java will have some nice improvement since we can keep all of that work within Java and never enter JRuby during execution (regexp + capture handling).