* Move sharding internal to StateManager
Avoid leaking sharding implementation details all over the State class and
breaking the API
* WiP StateManager based sharding
* Copy the state __dict__ when serializing to avoid breaking the instance
* State tests need to pass the correct substate token for redis
* state: when getting parent_state, set top_level=False
ensure that we don't end up with a broken tree
* test_app: get tests passing with redis by passing the correct token
refactor upload tests to suck less
* test_client_storage: look up substate key
* state.py: pass static checks
* test_dynamic_routes: working with redis state shard
* Update the remaining AppHarness tests to pass {token}_{state.get_full_name()}
* test_app: pass all tokens with state suffix
* StateManagerRedis: clean up commentary
* Expose preventDefault and stopPropagation for DOM events
All EventHandler, EventSpec, and EventChain can now carry these extra
"event_actions" that will be applied inside the frontend code when an event is
triggered from the DOM.
Fix#1621
Fix REF-675
* Test cases (and fixes) for "event_actions"
* form: from __future__ import annotations
for py38, py39 compat
* Revert overzealous merge conflict resolution
