(core) Accept values entered into Reference columns showing RowIDs without waiting.

Summary:
- Normally Reference columns can only be used for data entry once the target
  table has loaded. When it shows RowID, we shouldn't need to wait.
- Also, fix pasting values between cells of a RowID-showing column.

Test Plan: Added a test for entering data before data has loaded.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2902

app/client/lib/tableUtil.js

@@ -107,7 +107,7 @@ function makePasteHtml(tableData, selection, includeColHeaders) {
           let rawValue = col.rawGetter(rowId);
           let fmtValue = col.fmtGetter(rowId);
           let dataOptions = {};
-          if (rawValue != fmtValue) {
+          if (rawValue !== fmtValue) {
             dataOptions['data-grist-raw-value'] = JSON.stringify(rawValue);
           }
           return dom('td', dataOptions, fmtValue);