Add API to access config entries from KernelInfo (#26589)
## Description
This PR adds a new API function `KernelInfo_GetConfigEntries` that
allows custom operators to access all configuration entries from the
`OrtKernelInfo` object during kernel construction.
## Motivation and Context
Custom operators may need to access session configuration options to
adjust their behavior. Previously, there was no way to retrieve all
config entries from `KernelInfo`. This PR provides a convenient method
to get all configuration key-value pairs that were set on the
`OrtSessionOptions`.
## Changes
### API Additions
- **C API**: Added `KernelInfo_GetConfigEntries` function to `OrtApi`
(Version 1.24)
- Takes an `OrtKernelInfo*` as input
- Returns all config entries as `OrtKeyValuePairs*`
- Properly documented with usage examples
- **C++ API**: Added `GetConfigEntries()` method to `KernelInfoImpl`
template class
- Returns `KeyValuePairs` object
- Follows existing C++ wrapper patterns
### Implementation
- Implemented in `onnxruntime/core/session/custom_ops.cc`
- Iterates through `config_options_map` from `OpKernelInfo`
- Creates and populates `OrtKeyValuePairs` with all configuration
entries
### Testing
- Updated `shape_inference_test.cc` with test case
- Verifies config entries can be retrieved in custom kernel constructor
- Tests both existing and non-existing config keys
## Files Changed
- `include/onnxruntime/core/session/onnxruntime_c_api.h` - API
declaration
- `include/onnxruntime/core/session/onnxruntime_cxx_api.h` - C++ wrapper
declaration
- `include/onnxruntime/core/session/onnxruntime_cxx_inline.h` - C++
wrapper implementation
- `onnxruntime/core/session/custom_ops.cc` - Core implementation
- `onnxruntime/core/session/onnxruntime_c_api.cc` - API registration
- `onnxruntime/core/session/ort_apis.h` - API header declaration
- `onnxruntime/test/framework/shape_inference_test.cc` - Test coverage
## API Version
This change is part of ORT API Version 1.24.
## Breaking Changes
None. This is a backward-compatible addition to the API.
