Add context-free Call reinference and binding type propagation

[tqchen]

Summary

• Separate native context-free Call type inference from builder-dependent Relax and distributed inference, with strict read-only reinference from current Call inputs.
• Infer tirx.buffer_data from its BufferVar argument and reinfer after pointer storage-scope rewrites.
• Migrate TVM structural visit and mutation hooks to native tvm-ffi callbacks and remove the structural compatibility header.
• Propagate Bind and Let value type changes through their binder definitions and later uses while preserving unchanged node identity.
• Reuse existing Call result Type objects when inference establishes an equivalent result cheaply.