Implement DataFrameAnalyticsAuditMessage and DataFrameAnalyticsAuditor

[przemekwitek]

This PR implements new subclass of AbstractAuditor: DataFrameAnalyticsAuditor as well as a new subclass of AbstractAuditMessage: DataFrameAnalyticsAuditMessage.
It also:

• adds jobType field to AbstractAuditMessage so that anomaly detection audit messages and data frame analytics audit messages can be told apart in the common index (".ml-notifications")
• adds the new index template (".ml-notifications-000001") with the new field ("job_type") and "dynamic" setting set to "false"

Relates https://github.com/elastic/ml-team/issues/184

[przemekwitek]

run elasticsearch-ci/default-distro

[elasticmachine]

Pinging @elastic/ml-core

[przemekwitek]

run elasticsearch-ci/1

[przemekwitek]

run elasticsearch-ci/2

[przemekwitek]

run elasticsearch-ci/2

[benwtrent]

I think the only folks that read from this index is Kibana.

I hope that they use an index pattern to read. Do they already have code in flight to handle the situation where:

"job_type == null" => "anomaly detection"?

Just want to make sure that they are good to go with this change :).

[przemekwitek]

I think the only folks that read from this index is Kibana.

I hope that they use an index pattern to read. Do they already have code in flight to handle the situation where:

"job_type == null" => "anomaly detection"?

Just want to make sure that they are good to go with this change :).

Not yet, will coordinate with them before this PR is merged in.

[przemekwitek]

run elasticsearch-ci/bwc

[przemekwitek]

run elasticsearch-ci/bwc

[przemekwitek]

run elasticsearch-ci/bwc
run elasticsearch-ci/default-distro

[przemekwitek]

run elasticsearch-ci/1

[przemekwitek]

run elasticsearch-ci/bwc

[przemekwitek]

run elasticsearch-ci/bwc