Support to query number of collection property using /$count

[xuzhg]

1. /$count can append to collection navigation property within $expand

• ~/customers(1)?$expand=Orders/$count

The payload could be:

{
   "@odata.context": ....,
   "Id":1,
   ....
  "[email protected]": 5
}

The above scenario is valid, then it should be valid to do the same thing to non-navigation property.
So, Need to support:

2. /$count can append to primitive/complex collection property within $select

• ~/customers(1)?$select=Emails/$count

The payload could be:

{
   "@odata.context": ....,
   "[email protected]": 5
}

Be noted, from OData ABNF (Part):

select         = ( "$select" / "select" ) EQ selectItem *( COMMA selectItem )
selectItem     = STAR
               / allOperationsInSchema 
               / [ ( qualifiedEntityTypeName / qualifiedComplexTypeName ) "/" ] 
                 ( selectProperty
                 / qualifiedActionName  
                 / qualifiedFunctionName  
                 )
selectProperty = primitiveProperty  
               / primitiveColProperty [ OPEN selectOptionPC *( SEMI selectOptionPC ) CLOSE ]
               / navigationProperty
               / selectPath [ OPEN selectOption *( SEMI selectOption ) CLOSE
                            / "/" selectProperty 
                            ]


propertyPath = entityColNavigationProperty [ collectionNavigation ]
             / entityNavigationProperty    [ singleNavigation ]
             / complexColProperty          [ complexColPath ]
             / complexProperty             [ complexPath ]
             / primitiveColProperty        [ primitiveColPath ]
             / primitiveProperty           [ primitivePath ]
             / streamProperty              [ boundOperation ]

primitiveColPath = count / boundOperation / ordinalIndex

[xuzhg]

However, from OData ABNF, we can see the difference between $expand and $select

$expand	$select

For $expand, it explicitly mentions "/$count" after the expand path, but, there's no such "$count" after the select path?