(core) When searching, use formatter.formatAny() to handle values of invalid type.

Summary:
This turns out necessary because ReferenceList columns are formatted
using the formatter of the associated visibleCol. This works correctly
in dedicated widgets, but in generic code (like SearchModel here), this
formatter needs to handle unexpected values (of type ReferenceList).

Without the fix, it produces JS errors when search reaches a
RefList:<Date> column.

A better fix would allow a formatter to know that it expects a ReferenceList,
AND to know how to format each value of it, but that's a bigger question
that's outside the scope of this fix.

Test Plan: Includes a browser test which reproduces the bug.

Reviewers: cyprien

Reviewed By: cyprien

Differential Revision: https://phab.getgrist.com/D3195

app/client/models/SearchModel.ts

@@ -266,7 +266,7 @@ class FinderImpl implements IFinder {
     const value = this._sectionTableData.getValue(rowId, displayCol.colId.peek());
 
     // TODO: Note that formatting dates is now the bulk of the performance cost.
-    const text = formatter.format(value);
+    const text = formatter.formatAny(value);
     return this._searchRegexp.test(text);
   }