DeepSeek Blitz moe fusion (#37757)

### Ticket
[Link to Github
Issue](#35538)

### Problem description
Fuse routed expert and shared expert into one kernel.

### What's changed
Add internal looping into dram mm, for testing the same cb sharing.
Add moe gather, that swaps the logic for NC/BR, as using noc1 to send is
not interfering with dram read.
fuse moe routed/shared expert. 
Leave final reduce to one fusion for another pr, as that depends on the
merge of #37705 and
#37411

### Checklist

- [ ] [![All post-commit
tests](https://github.com/tenstorrent/tt-metal/actions/workflows/all-post-commit-workflows.yaml/badge.svg?branch=yugao/moe4)](https://github.com/tenstorrent/tt-metal/actions/workflows/all-post-commit-workflows.yaml?query=branch:yugao/moe4)
- [ ] [![Blackhole Post
commit](https://github.com/tenstorrent/tt-metal/actions/workflows/blackhole-post-commit.yaml/badge.svg?branch=yugao/moe4)](https://github.com/tenstorrent/tt-metal/actions/workflows/blackhole-post-commit.yaml?query=branch:yugao/moe4)
- [ ]
[![cpp-unit-tests](https://github.com/tenstorrent/tt-metal/actions/workflows/tt-metal-l2-nightly.yaml/badge.svg?branch=yugao/moe4)](https://github.com/tenstorrent/tt-metal/actions/workflows/tt-metal-l2-nightly.yaml?query=branch:yugao/moe4)
- [ ] New/Existing tests provide coverage for changes

Author: yugaoTT

models/demos/deepseek_v3_b1/fused_ops/moe/__init__.py

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+# SPDX-FileCopyrightText: © 2026 Tenstorrent AI ULC
+
+# SPDX-License-Identifier: Apache-2.0