(core) granular access control in the presence of schema changes

Summary:
 - Support schema changes in the presence of non-trivial ACL rules.
 - Fix update of `aclFormulaParsed` when updating formulas automatically after schema change.
 - Filter private metadata in broadcasts, not just fetches.  Censorship method is unchanged, just refactored.
 - Allow only owners to change ACL rules.
 - Force reloads if rules are changed.
 - Track rule changes within bundle, for clarity during schema changes - tableId and colId changes create a muddle otherwise.
 - Show or forbid pages dynamically depending on user's access to its sections. Logic unchanged, just no longer requires reload.
 - Fix calculation of pre-existing rows touched by a bundle, in the presence of schema changes.
 - Gray out acl page for non-owners.

Test Plan: added tests

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2734

sandbox/grist/acl.py

@@ -4,7 +4,7 @@
 
 import json
 
-from acl_formula import parse_acl_grist_entities
+from acl_formula import parse_acl_grist_entities, parse_acl_formula_json
 import action_obj
 import logger
 import textbuilder
@@ -128,7 +128,9 @@ def prepare_acl_col_renames(docmodel, useractions, col_renames_dict):
         patches.append(patch)
 
       replacer = textbuilder.Replacer(textbuilder.Text(formula), patches)
-      rule_updates.append((rule_rec, {'aclFormula': replacer.get_text().encode('utf8')}))
+      txt = replacer.get_text().encode('utf8')
+      rule_updates.append((rule_rec, {'aclFormula': txt,
+                                      'aclFormulaParsed': parse_acl_formula_json(txt)}))
 
   def do_renames():
     useractions.doBulkUpdateFromPairs('_grist_ACLResources', resource_updates)