* generate log messeges on invald certs

* server use _application_uri

* use correct socket method

* replaced os.path with pathlib.Path

* fixed some type hinting; added FIXME for critical vulnerability

* added string and path support for certificate paths because path only broke the API. BUT we should stop using strings for paths in the future..

---------

Co-authored-by: ratara <noreply>

* allow optional arrays

* is list fix for py 3.8

* finish optional array support

Fix `MonitoredItemServer._is_data_changed`, with as trigger `ua.DataChangeTrigger.StatusValueTimestamp` is used.

Currently with  `ua.DataChangeTrigger.StatusValueTimestamp` it only triggers when the SourceTimeStamp or the StatusCodes changes. Not on value updates.

According to Part 4 7.17.2 DataChangeFilter when the trigger is `ua.DataChangeTrigger.StatusValueTimestamp` is should trigger if either StatusCode, value or SourceTimeStamp changes.

No tests where available for monitored items, test added for this situation.

The value rank should be one dimension.

This is especially handy when the server runs behind NAT or inside docker container,
but a static EndpointUrl cannot be used because the host is multihomed.

* Python typing friendly
* Make optional basic type fields default None

Requires PR #1224 else the following tests will fail:
- test_common.py
  -	test_alias
    -		client
- test_unit.py
  - test_custom_structs

See discussion at #1067.

Allow registration of own (de)serializer for extension objects that are not in the ua namespace.
(see original TODO in code)

example:
```python
@dataclass
class YourDataType:

    data_type = ua.NodeId.from_string('''ns=2;i=3007''')

    Encoding: ua.UInt32 = field(default=0, repr=False, init=False, compare=False)
    ID: ua.String = ua.String()
    Description: Optional[ua.String] = None

ua.register_extension_object("YourDataType",
                                               ua.NodeId.from_string( f"ns=2;i=5002"),
                                               YourDataType,
                                                YourDataType.data_type)
```

When event is save it is added to  self._events[event.emitting_node], only that list is never initialized.

Makes typecheckers recognise the subclasses as Exceptions (#1204).

make sure we disconnect (in reality kill ThreadLoop) when we get an exception in `__enter__`in sync wrapper

Exceptions have already been handled and logged in _monitor_server_loop / _renew_channel_loop,
there is no need to log it again with higher loglevel

[xmlexporter] fix extensionobjects typeid indentifier missing namespace mapping to idx_in_exported_file

Other nodeids namespace are corrected to ``dx_in_exported_file`, only  the extensionobject typeid identifier isn't. Resulting in bad export.

Example:
```
<uax:ListOfExtensionObject>
        <uax:ExtensionObject>
          <uax:TypeId>
            <uax:Identifier>i=296</uax:Identifier>
          </uax:TypeId>
          <uax:Body>
            <uax:Argument>
              <uax:Name>MyFiled</uax:Name>
              <uax:DataType>
                <uax:Identifier>ns=3;i=3003</uax:Identifier>
              </uax:DataType>
```
In the case above `<uax:Identifier>ns=3;i=3003</uax:Identifier>` isn't corrected.
This can be easly fixed in `XmlExporter._val_to_etree` by using the lookup table `self._addr_idx_to_xml_idx`.

* Update server.py

* Update server.py

* add: unregister

* update: register procedure

* update: uaprocessor

* add: fixme

* fix: test

* fix: tests

Fixes #1180

OPC-UA specification Part 4, 5.6.3 specifies that a Null or empty user
token shall always be interpreted as anonymous. Add a test for this case
and a fix to properly handle it.