Support $index query option

[xuzhg]

Short summary (3-5 sentences) describing the issue.

Assemblies affected

OData .Net lib 7.x.

Requirement

OData spec says that:

5.1.10 System Query Option $index
The $index system query option allows clients to do a positional insert into a collection annotated with using the Core.PositionalInsert term (see [OData-VocCore]). The value of the $index system query option is the zero-based ordinal position where the item is to be inserted. The ordinal of items within the collection greater than or equal to the inserted position are increased by one. A negative ordinal indexes from the end of the collection, with -1 representing an insert at the end of the collection.

The [OData-ABNF] index syntax rule defines the formal grammar of the $index query option.

Please investigate, design, implement the $index query option.

[xuzhg]

Merged