Auditing for terminology: master/slave, *list, and others

[jsvd]

Let's audit and cleanup terminology with racial/slavery connotations!

Logstash has this repository, the individual plugin repos in https://github.com/logstash-plugins and other tooling repositories like https://github.com/elastic/docs-tools and https://github.com/elastic/logstash-devutils, https://github.com/elastic/jarvis.
For these it's necessary to migrate the master branch to be "main", but also look for any other terminology that may need to be changed.

master -> main:

• replace master references in elastic/logstash with main rename references of master branch to main branch #13301
• review CI (jenkins and travis)
  • [DOC] replace references to master branch with main #13302
  • change master branch reference to main logstash-plugins/.ci#26
  • https://github.com/elastic/infra/pull/32107
  • https://github.com/logstash-plugins/publisher/pull/1
• review documentation infrastructure (e.g. https://github.com/elastic/docs-tools)
  • change master branch references to main docs-tools#63
  • Switch Logstash repo from master to main for doc builds docs#2279
• review documentation itself (link references to master)
• default to main branch in new repos in logstash-plugins (done in org settings
• rename branches from master to main (repo list gist)

Other:

• review code references to terms such as blacklist and whitelist (example)
  • plan for an upgrade path if references exist in API or other user facing settings
• Known instances:
  • Move away from black/white list terminology logstash-plugins/logstash-filter-prune#28
  • https://www.elastic.co/guide/en/logstash/current/plugins-outputs-elasticsearch.html#plugins-outputs-elasticsearch-failure_type_logging_whitelist