onnxruntime

Refactor implementation of Tensor<T> and underlying buffer stores to improve binary size and maintainability (#5836)

* refactor tensor buffers to make cleaner

* refactor to make tensor backing buffer implementation smaller and cleaner

* missed virtual on destructor

* remove unnecessary static_pointer_cast

* add string vector accessor

Co-authored-by: Sheil Kumar <sheilk@microsoft.com>