chore: add anomaly provider interface

[srikanthccv]

Summary

Part of #5469

This is the main part of the PR. It describes how we arrive at the predicted value using the existing data. Supplementary reading https://about.gitlab.com/blog/2019/07/23/anomaly-detection-using-prometheus/

// anomalyParams is the params for anomaly detection
// prediction = avg(past_period_query) + avg(current_season_query) - avg(past_season_query)
//
//	                  ^                                  ^
//		              |                                  |
//			(rounded value for past peiod)    +      (seasonal growth)
//
// score = abs(value - prediction) / stddev (current_season_query)
type anomalyQueryParams struct {
	// CurrentPeriodQuery is the query range params for period user is looking at or eval window
	// Example: (now-5m, now), (now-30m, now), (now-1h, now)
	// The results obtained from this query are used to compare with predicted values
	// and to detect anomalies
	CurrentPeriodQuery *v3.QueryRangeParamsV3
	// PastPeriodQuery is the query range params for past seasonal period
	// Example: For weekly seasonality, (now-1w-4h-5m, now-1w)
	//        : For daily seasonality, (now-1d-2h-5m, now-1d)
	//        : For hourly seasonality, (now-1h-30m-5m, now-1h)
	PastPeriodQuery *v3.QueryRangeParamsV3
	// CurrentSeasonQuery is the query range params for current period (seasonal)
	// Example: For weekly seasonality, this is the query range params for the (now-1w-5m, now)
	//        : For daily seasonality, this is the query range params for the (now-1d-5m, now)
	//        : For hourly seasonality, this is the query range params for the (now-1h-5m, now)
	CurrentSeasonQuery *v3.QueryRangeParamsV3
	// PastSeasonQuery is the query range params for past seasonal period to the current season
	// Example: For weekly seasonality, this is the query range params for the (now-2w-5m, now-1w)
	//        : For daily seasonality, this is the query range params for the (now-2d-5m, now-1d)
	//        : For hourly seasonality, this is the query range params for the (now-2h-5m, now-1h)
	PastSeasonQuery *v3.QueryRangeParamsV3
}

[nityanandagohain]

some comments.

[nityanandagohain]

Looks good to start with.