Re-work GetAvailableProviders API (#14486)
### Description
Re-work `OrtApi::GetAvailableProviders` in a way that the data is
returned in a single allocation.
Fix exception safety issues and fix `Release` function.
Remove warning suppressions.
Fix exception safety issue in C++ API.
Fix exception safety issue in C# API.
Move EP name length enforcement to the implementation.
### Motivation and Context
The original motivation comes from
https://github.com/microsoft/onnxruntime/issues/14378.
However, the API is already implemented.
Cc: @prabhat00155
