Expose GetOrtvalueInitializer via provider bridge

[yuslepukhin]

Description

See the title

Motivation and Context

Make traditional EPs (non plug-in) access OrtValue initializers.

Re: #25747

[Copilot]

Pull Request Overview

This PR exposes the GetOrtValueInitializer functionality through the provider bridge to enable traditional execution providers (non-plugin) to access OrtValue initializers.

• Adds bridge methods for GetOrtValueInitializer in both Graph and GraphViewer classes
• Implements the provider host interface methods to delegate calls to the underlying graph objects
• Creates wrapper methods in the shared library provider types to enable external access

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
provider_bridge_ort.cc	Implements the bridge methods that delegate to the actual Graph and GraphViewer objects
provider_wrappedtypes.h	Adds wrapper methods for GetOrtValueInitializer in Graph and GraphViewer classes
provider_interfaces.h	Defines the virtual interface methods for the provider host

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