Improve MessageAudio peaks computation

There are two parts to this change:

1. The computation of peaks is moved from `MessageAudio` to the
   `GlobalAudioContext` and thus we can limit the concurrency of the
   computations (`p-queue`!) and de-duplicate the computations as well
2. While the peaks are computed the component has to display spinning
   animation instead of empty waveform and unclickable UI.

ts/util/lint/exceptions.json

@@ -16584,7 +16584,7 @@
     "rule": "React-useRef",
     "path": "ts/components/conversation/MessageAudio.js",
     "line": "    const waveformRef = react_1.useRef(null);",
-    "lineNumber": 144,
+    "lineNumber": 95,
     "reasonCategory": "usageTrusted",
     "updated": "2021-03-09T01:19:04.057Z",
     "reasonDetail": "Used for obtanining the bounding box for the container"
@@ -17055,4 +17055,4 @@
     "updated": "2021-01-08T15:46:32.143Z",
     "reasonDetail": "Doesn't manipulate the DOM. This is just a function."
   }
-]
+]