encapsulate calling FindItemByProperty

[junkmd]

IUIAutomationItemContainerPattern.FindItemByProperty is useful for finding matching elements in containers, but is inconvenient to use because it requires a null pointer and complicated arguments.

In the uiawrapper and uia_controls modules, direct referencing of such complex COM object methods to retrieve IUIAutomationElement and then passing it to the constructor of UIAElementInfo is overly responsible.
It is more appropriate that those be in the uia_element_info module.
So I defined the wrapper of UI item container in uia_element_info.

And I changed arguments passed to IUIAutomationItemContainerPattern.FindItemByProperty to be an instance of a more proper type.
As mentioned in #733 (comment) (317a7c9), if we try to create a null com pointer by passing 0 or None to uia_defs.IUIA().iuia.ElementFromHandle, an error will be raised.
I realized there is a simpler way to create a null com pointer. It is just doing POINTER(SubclassOfIUnknown)().

• reference: https://learn.microsoft.com/en-us/windows/win32/api/uiautomationclient/nf-uiautomationclient-iuiautomationitemcontainerpattern-finditembyproperty

[codecov]

Codecov Report

Merging #1328 (caeb3ec) into atspi (bf7f789) will decrease coverage by 6.32%.
The diff coverage is 97.14%.

Additional details and impacted files

@@            Coverage Diff             @@
##            atspi    #1328      +/-   ##
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- Coverage   94.15%   87.84%   -6.32%     
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  Files          60       60              
  Lines       23036    23053      +17     
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- Hits        21689    20250    -1439     
- Misses       1347     2803    +1456