[ML] Add custom rule parameters to force time shift

[valeriy42]

This PR extends the schema of the detection rule API by adding a new parametrizable action force_time_shift and a new property params to hold the parameter total_shift_amount as signed long in seconds to control the behavior of the time shift.

A valid schema looks like this:

POST _ml/anomaly_detectors/my_job/_update
{
	"detectors": {
		"detector_index": 0,
		"custom_rules": [
			// update the detector with a custom rule that forces a time shift of 1 hour back starting now
			{
				"actions": [
					"force_time_shift"
				],
				"params": {
					"force_time_shift": {
"time_shift_amount": 3600}
					}
				},
				"conditions": [{
					"applies_to": "time",
					"operator": "gt",
					"value": "now"
				},
{
					"applies_to": "time",
					"operator": "lt",
					"value": "now+bucket_span"
				},

]
			},
			...

Execution of the detection rule action force_time_shift will shift the time inside the anomaly detector by a specified amount. This is useful, e.g. to quickly adapt to the daylight saving time events that are known beforehand.

This PR is accompanied by changes in Kibana elastic/kibana#188710 and the native ml-cpp code elastic/ml-cpp#2690.

The integration tests between Java and C++ parts of the force-time shift action will be implemented in a separate PR.

[elasticsearchmachine]

Hi @valeriy42, I've created a changelog YAML for you.

[elasticsearchmachine]

Pinging @elastic/ml-core (Team:ML)