Missing Pipeline processors

[ThibautSF]

Comparing declared classes in Elastica\Processor against Elasticsearch documentation, some processors seem never to have been implemented.

• [x] Bytes -> #2008 (Merged)
• [ ] Circle
• [ ] CSV
• [ ] Dissect
• [x] Foreach -> #1813 (Merged)
• [ ] GeoIP
• [ ] Grok
• [ ] Gsub
• [ ] HTML strip
• [ ] Inference
• [ ] Pipeline
• [ ] Script
• [ ] Set security user
• [ ] URL decode
• [ ] User agent

[ThibautSF]

Link to #1810 & #1809

[ruflin]

Thanks for starting to track this!