Use Data frames response format (#1099)

* Use data frames for numeric data

* Use data frames for text data

* Use data frames for IT services

* fix multiple series

* Convert to the wide format if possible

* Fix table format for text data

* Add refId to the data frames

* Align time series from Zabbix API

* Fill gaps with nulls

* Fix moving average functions

* Option for disabling data alignment

* remove unused logging

* Add labels to data frames

* Detect units

* Set min and max for if percent unit used

* Use value mapping from Zabbix

* Rename unitConverter -> convertZabbixUnit

* More units

* Add missing points in front of each series

* Fix handling table data

* fix db connector data frames handling

* fix it services data frames handling

* Detect all known grafana units

* Chore: remove unused logging

* Fix problems format

* Debug logging: show original units

* Add global option for disabling data alignment

* Add tooltip for the disableDataAlignment feature

* Add note about query options

* Functions for aligning timeseries on the backend

pkg/timeseries/models.go

@@ -0,0 +1,18 @@
+package timeseries
+
+import "time"
+
+type TimePoint struct {
+	Time  time.Time
+	Value *float64
+}
+
+type TimeSeries []TimePoint
+
+func NewTimeSeries() TimeSeries {
+	return make(TimeSeries, 0)
+}
+
+func (ts *TimeSeries) Len() int {
+	return len(*ts)
+}