Properties Dialog Plugin: Only show "Details" tab if there are noteworthy details

Filter out all KFileItem properties (file type, size, modified date, etc) as those are all shown on the "General" tab and thus redundant.

Also, only add the "Details" tab if any details have been found afer this. This removes the tab if it is completely redundant (e.g. system files the user has no write access to). Unfortunately, most of the time this leaves the tab mostly blank with just Tags, Rating, Comment.

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Since this is all repo-internal I chose to just export a bunch of classes and mess with their internals for this.

Ideally, for KF6 we added a way for baloo-widgets to add some things to the "General" page, so that the "Details" page is only there if there is any actual additional information, such as Location and Author information…

This does not affect the Information panel in Dolphin which will still show all the information there is.

@ngraham @nicolasfella @felixernst

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After: