Use TensorPrimitives.Dot to calculate Dot Product

[luisquintanilla]

DotProduct is currently manually calculating DotProduct.

https://github.com/microsoft/mcp/blob/842d6bed7162ab37a0642134b3f07c305d584551/eng/tools/ToolDescriptionEvaluator/VectorDb/VectorDB.cs#L33-L50

TensorPrimitives provides a method for calculating Dot product.

https://learn.microsoft.com/en-us/dotnet/api/system.numerics.tensors.tensorprimitives.dot?view=net-10.0-pp

TensorPrimitives is already used for CosineSimilarity, so it would be good to maintain consistency.

https://github.com/microsoft/mcp/blob/842d6bed7162ab37a0642134b3f07c305d584551/eng/tools/ToolDescriptionEvaluator/VectorDb/VectorDB.cs#L20-L31