(core) add OWNERS='owners', EDITOR='editors', VIEWER='viewers' to condition formulas

Summary: this adds constants for user access roles, to facilitate autocomplete.

Test Plan: updated tests

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2761

app/client/aclui/ACLFormulaEditor.ts

@@ -42,6 +42,8 @@ export function aclFormulaEditor(options: ACLFormulaOptions) {
     return [
       // The few Python keywords and constants we support.
       'and', 'or', 'not', 'in', 'is', 'True', 'False', 'None',
+      // Some grist-specific constants:
+      'OWNER', 'EDITOR', 'VIEWER',
       // The common variables.
       'user', 'rec',
       // Other completions that depend on doc schema or other rules.