Support non-persisted properties

[AndriySvyryd]

Add a way to ignore a property for updates or queries, this is useful when the property value is always computed on the client, see #10768
Cosmos would use this to store the client key for entities in owned collections.

This would replace the relational IReadOnlyProperty.*IsStored methods

It could be configured separetely for different mapping types (Table, View, Sproc, etc.)

[ajcvickers]

@AndriySvyryd PropertySaveBehavior?

[AndriySvyryd]

@ajcvickers Are you suggesting to add another value, like IgnoreForQueryToo? That would be one way of implementing this.

[ajcvickers]

@AndriySvyryd Not really suggesting anything, just wondering how close it is to what we need.

[AndriySvyryd]

@ajcvickers PropertySaveBehavior currently only affects the update pipeline, we still need something for query, so I guess it's halfway there.

[AndriySvyryd]

1e6d85e implemented this in Cosmos by allowing to set "PropertyName" to an empty string.