#984 Updating indexedAt timestamps (#1024)

* add TimeElapsed util component, integrate into PostThreadItem

* integrate into posts

* use consistent naming

* use mobx and single interval for TimeElapsed

src/view/com/util/TimeElapsed.tsx

@@ -0,0 +1,21 @@
+import React from 'react'
+import {observer} from 'mobx-react-lite'
+import {ago} from 'lib/strings/time'
+import {useStores} from 'state/index'
+
+export const TimeElapsed = observer(function TimeElapsed({
+  timestamp,
+  children,
+}: {
+  timestamp: string
+  children: ({timeElapsed}: {timeElapsed: string}) => JSX.Element
+}) {
+  const stores = useStores()
+  const [timeElapsed, setTimeAgo] = React.useState(ago(timestamp))
+
+  React.useEffect(() => {
+    setTimeAgo(ago(timestamp))
+  }, [timestamp, setTimeAgo, stores.shell.tickEveryMinute])
+
+  return children({timeElapsed})
+})