Fix Opening for shared calendar for OL 2003

the important commit is the last one
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    openchangedb_property: Search String properties by PROP ID
    
    This way we handle both PT_UNICODE and PT_STRING8 type of properties.
    
    This commit fixes #7469 - can't share calendar bug
    The problem is that Outlook requests for PidTagContainerClass_string8
    property on Calendar folder. We assume this property should be UNICODE
    only and hence we return NOT_FOUND. This confuses Outlook a lot and
    it refuses to open a shared calendar.