[xnnpack][executorch] Pass xnnexecutor pointer to compileModel() (#89090)
Here we pass XNNExecutor* to compile model so that XNNExecutor can be allocated by runtime. This signature change is for executorch:
```
XNNExecutor compileModel(void* buffer) --> void compileModel(void* buffer, XNNExecutor* executor)
```
The intended usecase for allocating Executor and Compiling the serialized flatbuffer:
```
XNNExecutor* executor = runtime_allocator->allocateList<jit::xnnpack::delegate::XNNExecutor>(1);
XNNCompiler::compileModel(processed.buffer, executor);
```
Differential Revision: [D41208387](https://our.internmc.facebook.com/intern/diff/D41208387/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/89090
Approved by: https://github.com/digantdesai
