feat: PC-13045 Good total single query experimental support

[marcinlawnik]

Motivation

Enabling support for gathering godd and total points using single query.
Currently for Splunk only.

Sample YAML:

---
apiVersion: n9/v1alpha
kind: SLO
metadata:
  name: splunk-counts-calendar
  project: splunk
spec:
  service: splunk-service
  indicator:
    metricSource:
      kind: Agent
      name: splunk
      project: splunk
  timeWindows:
    - unit: Day
      count: 1
      calendar:
        startTime: 2021-04-09 00:00:00
        timeZone: Europe/Warsaw
  budgetingMethod: Occurrences
  objectives:
    - displayName: So so
      target: 0.80
      name: objective-1
      countMetrics:
        incremental: false
        goodTotal:
          splunk:
            query:  |-
              | mstats avg("spl.intr.resource_usage.IOWait.data.avg_cpu_pct") as n9good WHERE index="_metrics" span=15s 
              | join type=left _time [
              | mstats avg("spl.intr.resource_usage.IOWait.data.max_cpus_pct") as n9total WHERE index="_metrics" span=15s
              ]
              | rename _time as n9time
              | fields n9time n9good n9total

Summary

Added new goodTotal field to count metrics spec
Added validation for splunk query with new field names n9time, n9good, n9total

Testing

• Unit tests
• Manual planned tests after sloctl and platform changes

No release notes, as this is in experimental stage.