[TRT-EP] Add loadModelProto APIs (#25409)
### Description
This PR adds three new options for the TRT execution provider:
- trt_load_user_initializer
- trt_external_data_bytestream
- trt_external_data_bytestream_size
The idea is to use these options to leverage new TRT 10.13 APIs to give
the user more control on how the weights are loaded in the ONNX parser.
When `trt_load_user_initializer` is set to true, the EP will own the
weights instead of serializing the weights to ModelProto. This reduces
overhead in having to serialize large weights.
When `trt_external_data_bytestream / trt_external_data_bytestream_size`
is provided, the refitEngine() function will be able to read from this
bytestream directly to extract weights for the refitter.
Also fixes graph_proto_serializer to keep information about external
weights.
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Signed-off-by: Kevin Chen <kevinch@nvidia.com>
