Add Metrics test cases

[jkandasa]

Test cases for

Metrics types

• Availability
• Counter
• Gauge

Test types

• Functional test
  • Minimum, Maximum, Average, percentiles, limit, order, threshold
  • tag test
  • time range test
• Populate date for different range and validate with buckets (example: for an year)
• Validate automatic pruning of older data.