"rexml" was moved from default to bundled gems in ruby 3.0.0. This causes fluentd service to fail with the error "aws-sdk-core/xml/parser.rb in `set_default_engine': Unable to find a compatible xml library)". This fix provides default xml engine and fixes fluentd startup problem.
I added the most popular plugins (S3, kafka, kinesis, mongo, etc.)
and tried to bring it closer to the set of plugins they bundle with
td-agent, without getting rid of the ones we already have today. We
should probably make this overridable more generically going forward
but this should scratch most itches today.