onnxruntime

[TensorRT EP] Refactor of TRT plugins support (#17946)

Make sure "trt.plugins" custom op domain only being registered once.
The bottom line is "trt.plugins" custom op domain needs to be registered
before model load.

`CreateTensorRTCustomOpDomainList()` is TRT EP's function to create
"trt.plugins" custom op domain. Following are places where this function
will be called. (This function only fetches all the TRT plugins from TRT
plugin registry but not yet registered them to ORT custom op registry.
The real registration happens in AddCustomOpDomains())

C/C++ APIs:

- `OrtApis::SessionOptionsAppendExecutionProvider_TensorRT_XX`: This
function will make session option object contain the "trt.plugins"
custom op domain for ORT to register. So that later the session creation
api can register the custom op domain accordingly and won't complain
about invalid onnx node.
- `InferenceSession::RegisterExecutionProvider`: In some cases, users
might create the session object first and later call
session_object.RegisterExecutionProvider(). This function will call
p_exec_provider->GetCustomOpDomainList() which returns "trt.plugins"
custom op domain. Otherwise, session_object.Load(model) will complain.

Python APIs:

- `RegisterTensorRTPluginsAsCustomOps`: Need to call this function so
that session option object contains the "trt.plugins" custom op domain
for ORT to register.


Different language bindings have slightly different workflow of
initializing the session. This might cause duplicate custom op domain in
`session_option.custom_op_domains_` or
`CreateTensorRTCustomOpDomainList()` being called more than once, but we
put checks to make sure ep's custom op domain won't be registered twice.