Load measurements JSON with createStateFromQueryOrJSONs

Updating to support upcoming changes in Auspice from
<nextstrain/auspice#1881>

auspice_client_customisation/handleDroppedFiles.js

@@ -1,7 +1,6 @@
 import { createStateFromQueryOrJSONs } from "@auspice/actions/recomputeReduxState";
 import { errorNotification, warningNotification } from "@auspice/actions/notifications";
 import { Dataset, addEndOfNarrativeBlock, getDatasetNamesFromUrl } from "@auspice/actions/loadData";
-import { parseMeasurementsJSON } from "@auspice/actions/measurements";
 import { parseMarkdownNarrativeFile } from "@auspice/util/parseNarrative";
 import { parseMarkdown } from "@auspice/util/parseMarkdown";
 import { isAcceptedFileType as isAuspiceAcceptedFileType } from "@auspice/actions/filesDropped/constants";
@@ -123,15 +122,7 @@ async function collectDatasets(dispatch, files) {
         filesSeen.add(nameLower);
         const mainNameLower = nameLower.replace(`_${sidecarSuffix}.json`, '.json');
         if (datasets[mainNameLower]) {
-          // Parse measurements sidecars separately here.
-          // See https://github.com/nextstrain/auspice/pull/1663
-          if (sidecarPropName === 'measurements') {
-            datasets[mainNameLower][sidecarPropName] = readFile(file)
-              .then((json) => parseMeasurementsJSON(json))
-              .catch((err) => console.error("Failed to read and parse measurements sidecar", err));
-          } else {
-            datasets[mainNameLower][sidecarPropName] = readFile(file);
-          }
+          datasets[mainNameLower][sidecarPropName] = readFile(file);
           logs.push(`Read ${file.name} as a sidecar file of ${datasets[mainNameLower].name}`);
         } else {
           dispatch(errorNotification({
@@ -204,6 +195,7 @@ async function loadDatasets(dispatch, datasets, narrative) {
       pathnameShouldBe: "",
       ...createStateFromQueryOrJSONs({
         json: dataset1.main,
+        measurementsData: dataset1.measurements ? (await dataset1.measurements) : undefined,
         secondTreeDataset: dataset2 ? dataset2.main : null,
         query: {},
         narrativeBlocks: narrative,