Co-authored-by: Julien PRIGENT <julienprigent@wanadoo.fr>

This variable is used to trace server disconnections and renew the subscription/MI when it occurs.
Consequently is had to be unique urls otherwise it could grow indefinitely is some use-cases (i.e: reconciliator
is disabled or running slower that the Keepalive checks).

Support variables with properties in events and extend file generators for Alarms and Conditions (#415)

* Complete client alarms and conditions example

Complete client alarms and conditions example for usage with OPCFoundation UA-.NETStandard-Samples Quickstart AlarmConditionServer

* Add variables to generated event filter and event object

Event types can not only contain properties, but also variables. For example the ConditionType, which is the foundation of Alarms and Conditions, contains variables. Add the variables to the generated event filter and event object.

* Changed schemas for Fix localtime field of events

* changed schemas to autogenerate event_objects.py with conditions and alarms

* expand the event model with variables which are able to have properties as children
also supports custom events
now we are able to generate alarms and conditions

* Some refactoring and commenting in events and generate_model_event

* Newly generated event_objects with Alarms and Conditions Types and Variables
Co-authored-by: mar-ar <marco.arnold@hermle.de>
Co-authored-by: oroulet <oroulet@users.noreply.github.com>

* [InvalidSignature] Fix race condition with secure channel renewal

* [InvalidSignature] Clean code and add tests

* [InvalidSignature] Consider expired SecureToken for up to 25% of its lifetime
Co-authored-by: Julien Prigent <julienprigent@wanadoo.fr>

* unlucky default value for ResultMask!

@oroulet good that you asked... but i was to slow! sorry about that -_-°

* Update client.py

* cast to list

* added test

* fix missing import

* unlucky default value for ResultMask!

@oroulet good that you asked... but i was to slow! sorry about that -_-°

* Update client.py

* added browse multiple nodes in one ua call

https://reference.opcfoundation.org/v104/Core/docs/Part4/5.8.2/

* Update client.py

Smaller code cleanups like "adding var" since it is not already declared, removing unused import statementes and similar.

Rewrite if statement to easier readable code
Replace Path expressions a better way?
Add absolute to get absolute path to file (I hope)
Remove one obsolete import pytest
Refactor method name to better name
Redo nested if statement a better way
Remove forgotten garbage methods
Replace os path with pathlib
Small Codestyle fixes
Add check if both or neither xml arg was passed -> not xor
Fix wrong required model handling
Differ between xmlstrin and file
Add tests for requirement check
Add two xml files for test purposes
Replace ImportError with Exception
Remove unused var
List all missing requirements
Check server models in seperate Coroutine
Add method to check requirements while xmlimport
Add namespaces Node to Shortcuts

* uals -l option fix

uals -l option conversion to async was incomplete and failed with error
TypeError: 'coroutine' object is not iterable.

* Fix obsolete server-example.py reference and remove unused _logger

* [HaClient] Asyncua client wrapper

It exposes an interface similar to Client. You'll find some examples
and tests to guide you through this new feature.

Under the hood, it starts a keepalive task to monitor the status and
service level for each server.

It also includes an HaManager task which promotes a primary and
reconnect unhealthy clients. Unhealthy clients are detected based
on the socket status and keepalive data collected.

The requests received by users as well as the HaManager decisions
produce an ideal state called the "ideal_map". Regularly, the reconciliator task
kicks in, lock this configuration, and applies the "ideal_map" configuration.
It then stores the actual subscriptions status into the "real_map" using the
lower level components of the library.

Current limits:

- We only support HA WARM mode and datachange notifications (no event/status_change).
_ We support multiple subscriptions, but a node should only be subscribed once.

Component details:

- HaClient:
    - Configuration based on dataclasses: HaConfig (required) and HaConfigSecurity (optional)
    - Responsible to start up sides tasks: keepalive, hamanager, reconciliator
    - Mutates the ideal_map via VirtualSubscription
    - Generic hooks (i.e: to monitor subscription performance)

- KeepAlive (task):
    - Regularly hits the server to check its service_level / status.

- HaManager (task):
    - Promote primary / secondaries
    - Reconnect disconnected/unhealthy client based on the keepalive
    feedback.

- Reconciliator (task):
    - Applies the ideal configuration
    - Perform checks on the call responses
    - Mutates the real_map

- VirtualSubscription:
    - Key component of the ideal and real maps.
    - Exposes an interface similar to the subscription but only
    store the settings.

* [HaClient] fix test for py3.8/py3.9

CancelledError and TimeoutError have moved from concurrent.futures to
asyncio. Note that CancelledError now inherits from BaseException and
not Exception anymore. See https://bugs.python.org/issue32528 for the
details.
Finally, fix pytest_yield_fixture deprecation

* [HaClient] address the comments (utils + refacto reconciliator)
Co-authored-by: oroulet <oroulet@users.noreply.github.com>