onnxruntime

Improve custom op library handle cleanup (#14099)

### Description
- Adds a new C API `OrtApi::RegisterCustomOpsLibrary_V2` that manages
the lifetime of dynamic library handles (i.e., calls `dlclose` or
`FreeLibrary`).
- Deprecates C API `OrtApi::RegisterCustomOpsLibrary`.
- Adds C++ API wrapper for convenient registering of custom op
libraries.
- `PySessionOptions` is now an alias of `OrtSessionOptions`

### Motivation and Context
The current API for registering custom op libraries loads dynamic
libraries but requires users to handle the release of the corresponding
library handles. Additionally, the user has to make sure to release the
library handle _after_ the session has been destroyed (or the program
segfaults).

The new API automatically cleans up the library and allows the user to
write more straightforward code.