Add 2 C API for ort extension (#19808)
### Description
<!-- Describe your changes. -->
Add 2 C API for ORT extension:
- KernelInfo_GetAllocator
- OrtCustomOp::GetMayInplace
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Add 2 C API for ORT extension project, which will leverage these 2 APIs
for GroupQueryAttention custom op.
