(core) Checks that an ACL formula can be parsed, and prevent saving unparsable ACL rules.

Summary:
- Fix error-handling in bundleActions(), and wait for the full bundle to complete.
  (The omissions here were making it impossibly to react to errors from inside bundleActions())
- Catch problematic rules early enough to undo them, by trying out ruleCollection.update()
  on updated rules before the updates are applied.
- Added checkAclFormula() call to DocComm that checks parsing and compiling
  formula, and reports errors.
- In UI, prevent saving if any aclFormulas are invalid, or while waiting for the to get checked.

- Also fixed some lint errors

Test Plan: Added a test case of error reporting in ACL formulas.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2689

sandbox/grist/main.py

@@ -9,6 +9,7 @@ sys.path.append('thirdparty')
 import marshal
 import functools
 
+from acl_formula import parse_acl_formula
 import actions
 import sandbox
 import engine
@@ -110,6 +111,7 @@ def main():
   def get_formula_error(table_id, col_id, row_id):
     return objtypes.encode_object(eng.get_formula_error(table_id, col_id, row_id))
 
+  export(parse_acl_formula)
   export(eng.load_empty)
   export(eng.load_done)