Add array overloads to ArrayAppend, ArrayPrepend and ArrayInsert

Follow up to NCBC-2091 to re-introduce methods for appending, prepending, inserting multi-values to an array.

The methods ArrayAppend, ArrayPrepend and ArrayInsert require that the brackets be removed while serializing the commands/body and just before sending. In v2 we use the method StripBrackets to do this to the byte array if the operation type has a flag set for removing brackets:

https://github.com/couchbase/couchbase-net-client/blob/release27/Src/Couchbase/IO/Operations/SubDocument/SubDocSingularMutationBase.cs#L74-L77

The method StripBrackets is defined here:

https://github.com/couchbase/couchbase-net-client/blob/release27/Src/Couchbase/Utils/ArrayExtensions.cs#L156-L165

This needs to be ported and integrated with the newer buffer manager code nin v3; its not a direct port unfortunately as the newer buffering is contiguous.