Include originating function in C-API catch-all exception message

[GopalakrishnanN]

Description

The terminal catch (...) handler in the API_IMPL_END macro returned ORT_FAIL with the literal string "Unknown Exception":

catch (...) {
  return OrtApis::CreateStatus(ORT_FAIL, "Unknown Exception");
}

For any non-std::exception throwable that crosses the C ABI (rare, but e.g. a thrown integer from third-party code), this discarded all context, including which C-API function it surfaced in. This change records the originating function via MakeString(..., __func__):

catch (...) {
  return OrtApis::CreateStatus(ORT_FAIL, ::onnxruntime::MakeString("Unknown exception in ", __func__).c_str());
}

API_IMPL_END expands at the end of each C-API function body, so __func__ resolves to the function where the unknown exception was caught. MakeString is already available (error_code_helper.h includes core/common/make_string.h), and CreateStatus copies the message, so the temporary is safe.

Only the catch-all diagnostic message changes. The OnnxRuntimeException / NotImplementedException / std::exception handlers and all normal execution paths are unaffected.

Motivation and Context

Small diagnostic improvement flagged in an error-handling review (item EH3): the catch-all funnel collapsed to a context-free string, making a non-std::exception failure that reaches the C ABI hard to localize. Naming the originating function turns "something threw somewhere" into "something threw in OrtApiName".

Testing

Built onnxruntime_test_all (Release, Windows) — compiles cleanly across the C-API translation units that use API_IMPL_END; InferenceSessionTests smoke test passes on the rebuilt binary.

Note: the catch (...) path fires only for a non-std::exception throwable, which cannot be triggered from a unit test without editing production code, so this is a compile-verified diagnostic-only change.