Enhance EP demo runtime configuration

[01Chen]

Summary

• Make the EP dispatch demo use runtime shape configuration for bs, h, and topK instead of fixed constants.
• Add demo modes for dispatch-combine, dispatch-only, and combine-only, including seeded combine-only inputs and separate dispatch/combine validation output.
• Extend the local demo runner to forward named options such as --bs, --h, --k, --mode, TP, shared expert, active mask, and quantization settings while preserving the existing positional form.
• Add source checks covering runtime shape config, combine-only mode, and runner named arguments.

Validation

• git diff --check -- tests/ep/demo/run_tilexr_ep_dispatch_demo.sh tests/ep/demo/tilexr_ep_dispatch_demo.cpp tests/ep/unit/test_tilexr_ep_kernel_sources.cpp
• bash -n tests/ep/demo/run_tilexr_ep_dispatch_demo.sh
• g++ -std=c++14 tests/ep/unit/test_tilexr_ep_kernel_sources.cpp and ran the resulting source-check binary