Restore interval dropdown (#220)

Was accidentally removed

frontend/src/components/company-survey-v2/time-series/interval-dropdown.tsx

@@ -0,0 +1,29 @@
+import {FunctionComponent} from "react"
+import {Dropdown} from "primereact/dropdown"
+import {isoStringToDateTimeUnit, dateTimeUnitToIsoString} from "zero-zummon"
+import {SelectItem, SelectItemOptionsType} from "primereact/selectitem"
+
+const options: SelectItemOptionsType = [
+    {
+        value: "PT15M",
+        label: "Kwartier",
+    },
+    {
+        value: "P1D",
+        label: "Dag",
+    },
+    {
+        value: "P1M",
+        label: "Maand",
+    },
+]
+
+export const IntervalDropdown: FunctionComponent<{
+    timeStep: any,
+    setTimeStep: (timeStep: any) => void
+}> = ({timeStep, setTimeStep}) => {
+
+    return (
+        <Dropdown options={options} value={dateTimeUnitToIsoString(timeStep)} onChange={event => setTimeStep(isoStringToDateTimeUnit(event.value))}/>
+    )
+}

frontend/src/components/company-survey-v2/time-series/time-series-textarea.tsx

@@ -7,6 +7,7 @@ import {LabelRow} from "../generic/label-row"
 import {displayTimeZone, kotlinInstantToJsJodaInstant, prettyPrint} from "./time-series-util"
 import {Dropdown} from "primereact/dropdown"
 import {InputText} from "primereact/inputtext"
+import {IntervalDropdown} from "./interval-dropdown"
 
 const placeholder = `
 bijvoorbeeld:
@@ -50,6 +51,9 @@ export const TimeSeriesTextarea: FunctionComponent<{timeSeries: TimeSeries, setT
             <LabelRow label="Tijdzone">
                 <Dropdown options={[{ label: 'Nederlandse tijd', value: displayTimeZone }]} value={displayTimeZone}/>
             </LabelRow>
+            <LabelRow label="Meetinterval">
+                <IntervalDropdown timeStep={internalTimeSeries.timeStep} setTimeStep={timeStep => setTimeSeriesImpl(internalTimeSeries.withTimeStep(timeStep))} />
+            </LabelRow>
             <LabelRow label="Plak hier de waarden in kWh">
                 <InputTextarea
                     id="values"