Initial version of the SNMP integration plugin, incorporating snmp and snmptrap inputs

[edmocosta]

What does this PR do?

Created the SNMP Integration Plugin, incorporating the logstash-input-snmp and logstash-input-snmptrap plugins.

• No code changes were done, only small fixes, adjustments and project structure moves.
• A flaky test was fixed and the .ci adjusted to work with both plugins. It was mainly adapted from the original CI configurations.
• Unit tests and integration tests were placed into two separate folder spec/integration and spec/unit. The specs were not modified.
• Docs were adjusted to follow the integration plugins pattern:
  • index.asciidoc: summarizes the provided plugins
  • input-snmp.asciidoc: no changes from the original input plugin but the header :type: integration markups
  • input-snmptrap.asciidoc: no changes from the original input plugin but the header :type: integration markups

Checklist

• [ ] My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• [ ] I have added tests that prove my fix is effective or that my feature works

Related issues

[karenzone]

@edmocosta Thank you for the opportunity to work through adding an integration iteratively. We might still hit some bumps, but we'll learn the best practices and then I'll document them for next time.