(core) make ValueFormatter.format honor its return type

Summary: make ValueFormatter.format honor its return type

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D2663

app/common/ValueFormatter.ts

@@ -56,7 +56,7 @@ export class BaseFormatter {
    * classes to handle values in formatter-specific ways.
    */
   public format(value: any): string {
-    return value;
+    return String(value);
   }
 
   /**

app/server/serverMethods.js

@@ -105,7 +105,7 @@ function makeCSV(activeDoc, viewSectionId, sortOrder, req) {
     rowIds.forEach(row => {
       csvMatrix.push(access.map((getter, c) => formatters[c].formatAny(getter(row))));
     });
-    return csv.stringifyAsync(csvMatrix, {formatters: {bool: v => '' + Number(v)}});
+    return csv.stringifyAsync(csvMatrix);
   });
 }
 exports.makeCSV = makeCSV;