feat(schemaExplorer): introduce rangeArguments helper

ui/src/flux/helpers/rangeArguments.ts

@@ -0,0 +1,8 @@
+import {TimeRange} from 'src/types'
+
+export default function rangeArguments(timeRange: TimeRange): string {
+  const start = timeRange.lowerFlux ? timeRange.lowerFlux : timeRange.lower
+  return timeRange.upper
+    ? `start: ${start}, stop: ${timeRange.upper}`
+    : `start: ${start}`
+}

ui/test/flux/helpers/rangeAguments.test.ts

@@ -0,0 +1,12 @@
+import rangeArguments from 'src/flux/helpers/rangeArguments'
+
+describe('Flux.helpers.rangeArguments', () => {
+  it('formats relative time range', () => {
+    expect(rangeArguments({lower: 'xyz', lowerFlux: '-10s'})).toBe(
+      'start: -10s'
+    )
+  })
+  it('formats absolute time range', () => {
+    expect(rangeArguments({lower: 'a', upper: 'b'})).toBe('start: a, stop: b')
+  })
+})