Charts: Dual x-axis support for all historical charts

All historical charts have a button that enables switching between the 
twox-axis types namely: Block Height and Block Time. A group button at 
the chart bottom was added to enable easy swapping of either of the two 
x-axis. Since dygraph doesn't support display of multiple x-axis the two 
distinct x-axes cannot not be displayed together.

No changes to the data stored in charts cache was made to enable an 
extra x-axis to be swapped on a chart with the same y-axis data set. The 
query below allows the index of each record retrieved to be used like a 
Block Height since the query is ordered by height. Therefore no extra 
data is required when the bin value is set to blocks.

SelectBlockStats = `SELECT height, size, time, chainwork, numtx
	FROM blocks
	WHERE is_mainchain
        AND height > $1
	ORDER BY height;`

When the bin value is set to day, a pre-populated height array entry
existed.

* Add the UI axis selector buttons stimulusjs controls

* Add height axis to all historical charts

* Fix ticket price and pow difficulty height x-axis values

* Fix the coins supply chart

* Rename zoom variables to bin

* Keep support for the deprecated zoom parameter

* Delete redundant zoom_helper implementations

* Fix the broken slider zoom selector feature

* Optimize the mapKey for legacy URLs and slider zoom features

Author: dmigwi

api/apiroutes.go

@@ -1602,11 +1602,16 @@ func (c *appContext) getAddressTxAmountFlowData(w http.ResponseWriter, r *http.R
 
 func (c *appContext) ChartTypeData(w http.ResponseWriter, r *http.Request) {
 	chartType := m.GetChartTypeCtx(r)
-	zoom := r.URL.Query().Get("zoom")
-	chartData, err := c.charts.Chart(chartType, zoom)
+	bin := r.URL.Query().Get("bin")
+	// Support the deprecated URL parameter "zoom".
+	if bin == "" {
+		bin = r.URL.Query().Get("zoom")
+	}
+	axis := r.URL.Query().Get("axis")
+	chartData, err := c.charts.Chart(chartType, bin, axis)
 	if err != nil {
 		http.NotFound(w, r)
-		log.Warnf(`Error fetching chart %s at zoom level '%s': %v`, chartType, zoom, err)
+		log.Warnf(`Error fetching chart %s at bin level '%s': %v`, chartType, bin, err)
 		return
 	}
 	writeJSONBytes(w, chartData)