(core) Don't clear widget options when changing column type

Summary: Previously, changing the type of a column would clear its widget options and conditional style rules by default, with a few exceptions to explicitly keep them. This diff reverses that behaviour, keeping the options by default.

Test Plan: Updated several existing tests, plus lots of manual testing.

Reviewers: cyprien

Reviewed By: cyprien

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3491

sandbox/grist/test_useractions.py

@@ -104,7 +104,6 @@ class TestUserActions(test_engine.EngineTestCase):
     self.assertPartialOutActions(out_actions, { "stored": [
       ['ModifyColumn', 'Schools', 'city', {'type': 'Ref:Address'}],
       ['UpdateRecord', 'Schools', 4, {'city': 0}],
-      ['UpdateRecord', '_grist_Views_section_field', 1, {'widgetOptions': ''}],
       ['UpdateRecord', '_grist_Tables_column', 23, {
         'type': 'Ref:Address', 'widgetOptions': 'world'
       }],