(core) Extending Google Drive integration scope

Summary:
New environmental variable GOOGLE_DRIVE_SCOPE that modifies the scope
requested for Google Drive integration.
For prod it has value https://www.googleapis.com/auth/drive.file which leaves
current behavior (Grist is allowed only to access public files and for private
files - it fallbacks to Picker).
For staging it has value https://www.googleapis.com/auth/drive.readonly which
allows Grist to access all private files, and fallbacks to Picker only when the file is
neither public nor private).
Default value is https://www.googleapis.com/auth/drive.file

Test Plan: manual and existing tests

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3038

test/nbrowser/gristUtils.ts

@@ -638,7 +638,7 @@ export async function importFileDialog(filePath: string): Promise<void> {
     await driver.findWait('.test-dp-add-new', 1000).doClick();
     await driver.findContent('.test-dp-import-option', /Import from file/i).doClick();
   });
-  await driver.findWait('.test-importer-dialog', 1000);
+  await driver.findWait('.test-importer-dialog', 5000);
   await waitForServer();
 }