(core) Summary columns improvemnt.

Summary:
Improving user experience on summary columns.
- Showing 'not-allowed' cursor on sections/menus that can't be changed
- Disabling menu options and buttons in the column behavior section that converts a formula column to a data column
- Showing nicer error message about converting formula to a data column.

Test Plan: manual tests, no behavior change

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3222

app/client/ui/RightPanel.ts

@@ -556,6 +556,12 @@ export const cssRow = styled('div', `
   }
 `);
 
+export const cssBlockedCursor = styled('span', `
+  &, & * {
+    cursor: not-allowed !important;
+  }
+`);
+
 export const cssButtonRow = styled(cssRow, `
   margin-left: 0;
   margin-right: 0;